INVERTEBRATE ZOOLOGY - H. I. Shcherbak - 2008

KINGDOM MULTICELLULAR ANIMALS (METAZOA)

SUBKINGDOM TRUE MULTICELLULAR ANIMALS (EUMETAZOA)

DIVISION TRIPLOBLASTIC (TRIPLOBLASTICA) OR BILATERAL (BILATERIA) ANIMALS

SUBDIVISION MOLTING ANIMALS (ECDYSOZOA)

PHYLUM ARTHROPODS (ARTHROPODA)

SUBPHYLUM TRACHEATES (TRACHEATA)

SUPERCLASS HEXAPODS (HEXAPODA)

CLASS INSECTS (INSECTA), OR ECTOGNATHS (ECTOGNATHA)

SUBCLASS PTERYGOTES (PTERYGOTA)

Pterygotes comprise the vast majority of insect species. They possess well-developed wings, although in some species the wings are reduced or entirely absent due to a cryptic or parasitic lifestyle (e.g., lice). Winged adults (imagines) generally do not molt (with the exception of mayflies). Based on The Nature of their metamorphosis, insects are divided into two major groups.

Insects with incomplete metamorphosis (Hemimetabola)

Order Mayflies (Ephemeroptera). About 200 species are known, with over 100 species in Ukraine. These are insects of various sizes (ranging from a few millimeters to 4–5 cm).

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Fig. 381. Common mayfly (Ephemera vulgata) (from Dogel): a - naiad; b - subimago; c — imago

The body of the imago is elongated, and mouthparts are reduced (imagines do not feed, though they are capable of drinking Water). They possess short, bristle-like antennae, a pair of large compound eyes, and three simple ocelli. The wings are reticulated, with the hind pair typically smaller than the fore pair, and occasionally completely reduced (Fig. 381). The abdomen is elongated, bearing a pair of long, bristle-like cerci and often an unpaired paracercus at the tip.

Development occurs in fresh water via archimetaboly: a larva emerges from the egg possessing nearly homonomous metamerism, underdeveloped antennae, caudal filaments, and eyes. After molting, it transforms into a nymph-like larva that already features fully formed antennae and caudal filaments, faceted eyes, and tracheal gill buds. By the fifth or sixth instar, wing pads appear, and the larva develops into a nymph equipped with tracheal gills. The final-instar nymph gives rise to an immature winged stage—the subimago—which then molts to transform into the sexually mature adult phase, the imago. Larval feeding habits are highly diverse, encompassing predatory forms, filter feeders, and species that feed on detritus, silt, and other organic matter. Development lasts anywhere from several months to two or three years.

Fertilization and egg-laying in most species occur within a few hours after The Emergence of the imago. Adults die shortly thereafter, hence the Ukrainian common name "one-day flies" (mayflies). The most widespread species in Ukraine is the two-winged mayfly *Cloeon dipterum*. Mayfly larvae and nymphs constitute a vital food component for numerous freshwater fish species, particularly cyprinids.

Order Cockroaches (Blattoptera). Over 3,000 species are known, with about 20 species occurring in Ukraine. Their length ranges from 1 to 10 cm. The body is dorsoventrally flattened. Mouthparts are biting-chewing, antennae are long and filiform, and compound eyes are well developed. The forewings are thickened and leathery, modified into tegmina; the hind wings are membranous, and reduced in some species. The abdomen consists of eight to ten segments (Fig. 376).

Cockroaches inhabit primarily tropical and subtropical regions, feeding mainly on plant or animal remains. Two synanthropic cockroach species are known in Ukraine: the German cockroach, or dusken / prusak (*Blattella germanica*), 10–13 mm long, and the oriental cockroach (*Blatta orientalis*), 30 mm long. Both species are of tropical origin and consequently dwell exclusively in heated indoor environments in Ukraine, where they feed on food scraps and may damage books, leather goods, and other items. They are recognized as mechanical vectors of the dysentery bacillus, the typhoid fever pathogen, and helminth eggs (such as whipworms and pinworms). Recently, the larger American cockroach (*Periplaneta americana*, about 50 mm long) has spread in urban areas. The common Lappish cockroach (*Ectobius lapponicus*), which feeds on Lichens, leaf litter, and similar matter, is widespread in forests.

Order Praying Mantises (Mantoptera). In total, there are over 2,000 species, distributed predominantly in the tropics. Six species are known in Ukraine, primarily in Crimea.

These are large predatory insects (up to 15 cm long). The body is elongated, sometimes broadened; the HEAD is triangular, featuring biting mouthparts, long whip-like antennae, and large eyes capable of rotating nearly 360°. The prothorax is elongated and bears raptorial forelegs of a characteristic Structure. The forewings are modified into narrowed tegmina, while the hind wings are fan-shaped, membranous, and occasionally reduced. The abdomen consists of 10 segments (Fig. 382).

Fig. 382. European mantis (*Mantis religiosa*) (from Pravdin)

Praying mantises are ambush predators that lie in wait for their prey (mostly insects) by sitting motionlessly on shoots, tree bark, and other surfaces. They possess protective coloration and a stick- or leaf-like body shape. The European mantis (*Mantis religiosa*) inhabits Crimea and the steppe and forest-steppe zones of Ukraine, reaching a length of 75 mm. Most mantis species are listed in the Red Data Book of Ukraine.

Order Termites (Isoptera). This order comprises social insects characterized by individual polymorphism (Fig. 383). About 2.5 thousand species are known globally, with only one species found in Ukraine.

Body length ranges from a few millimeters to 2-3 cm. Mouthparts are of the chewing type; eyes are small and well-developed only in reproductive individuals, while sterile forms often lack them entirely. The Thorax is flattened. Two pairs of elongated, approximately equal membranous wings with longitudinal venation are present exclusively in reproductive forms. The abdomen consists of 10 segments.

Termites are social insects. A colony typically includes a pair of reproductives (the "queen" and the "king") alongside hundreds to millions of sterile, wingless individuals incapable of reproduction, which are usually divided into castes such as workers and soldiers. Additionally, during certain periods (prior to swarming), the colony produces numerous winged males and females. These undertake a nuptial flight, after which they pair up, shed their wings, and establish new colonies. Pheromones play a crucial role in regulating the social life of termites.

Termites build nests in the soil, decaying wood, and tree crowns. In tropical regions, clay termite mounds can reach heights of 5 meters or more. In deserts, by contrast, termite nests may extend 12-15 meters deep into the ground.

Fig. 383. Various castes of the termite Reticulitermes lucifugus (from Dogel): a - worker; b - soldier; c - winged reproductive individual;

d - female that has shed its wings after mating; e — female during egg-laying

Many termite species feed on animal and plant detritus. Some cultivate specific species of Fungi within their nests for consumption. Only worker termites feed independently; they also nourish the reproductives, soldiers, and early-instar nymphs using salivary gland secretions. Highly specialized species feed on wood (Cellulose). Their gut harbors flagellates of the order Hypermastigida, which secrete the enzyme cellulase. This enzyme breaks down plant fiber, as termites themselves cannot produce it. Furthermore, many species host symbiotic nitrogen-fixing Bacteria, providing an additional source of Proteins.

Termites are inhabitants of tropical and subtropical regions.

Only a few species extend into temperate zones.

In the steppe zone of Ukraine, the Mediterranean termite Reticulitermes lucifugus is known to damage wooden structures, destroy books, and cause similar havoc. There is a documented case in South Africa where termites completely destroyed an entire town built of wooden structures. In nature, termites play a vital role in soil formation.

Fig. 384. Orthopterans (from Pravdin, with modifications):

a - green bush-cricket (Tettigonia viridissima); b - steppe cricket (Gryllus desertus); c - mole cricket, or common mole cricket (Gryllotalpa gryllotalpa)

Order Orthoptera. This order includes over 20,000 species, approximately 200 of which are found in Ukraine.

Orthopterans are characterized by chewing mouthparts and two pairs of wings: the forewings are leathery, narrow, and straight (giving the order its name), functioning as tegmina, while the hindwings are broad, membranous, and fan-folded beneath the forewings at rest. The hind legs are adapted for jumping, and the abdomen has ten segments (Fig. 384).

A distinctive feature of orthopterans is their ability to produce and perceive sound. Acoustic signals feature species-specific frequencies and vibration amplitudes. In bush-crickets and grasshoppers, the sound-producing apparatus is located on the forewings, consisting of a system of serrated Veins that rub against each other. Hearing Organs are situated on the tibias of the forelegs. In locusts, sounds are produced by the friction of small Teeth on the hind legs against the forewing veins, while hearing organs are located on the sides of the first thoracic segment.

Orthopterans include bush-crickets, true crickets, and mole crickets—which feature long, thread-like antennae and long, knife-like ovipositors in females—as well as short-horned grasshoppers and locusts with short antennae. The most widespread species in Ukraine are the green bush-cricket (Tettigonia viridissima), which reaches 4 cm in length, and the house cricket (Acheta domestica), which inhabits human dwellings. The European mole cricket (Gryllotalpa gryllotalpa), growing up to 5 cm long, inhabits moist soils and poses a serious threat to garden crops by damaging roots and underground shoots.

The migratory locust (Locusta migratoria) reproduces in river floodplains. During years of mass outbreaks, nymphs gather in huge swarms (bands) numbering billions of individuals with a combined biomass of hundreds of thousands of tons. In search of food, adults fly hundreds of kilometers, stripping away all vegetation in their path. Alongside the migratory locust, numerous other locust species are found across every continent. The economic Damage caused by locusts amounts to tens of billions of dollars annually.

Order Anoplura (Sucking Lice). This group comprises about 200 species of mammalian ectoparasites ranging from 0.4 to 6 mm in length. Mouthparts are piercing-sucking; some species possess two simple ocelli, and antennae are shortened. All thoracic segments are fused together, wings are absent, and legs are robust, terminating in claw-like structures that fold like a pocketknife—an adaptation used to cling to hairs. The body is dorsoventrally flattened (Fig. 385).

Fig. 385. Human body louse (Pediculus humanus humanus) (from Giliarov): a - adult insect; b - egg (nit)

Each species of louse typically lives on the body of one or several closely related host species. Examples include the hog louse, cattle louse, and other parasites of farm animals. Parasitizing humans are the pubic louse (Phthirus pubis), which does not transmit disease pathogens, and the human louse (Pediculus humanus), which includes two subspecies: the head louse and the body louse. This species acts as a vector for dangerous diseases such as epidemic typhus and relapsing fever.

Order Hemiptera (Homoptera) encompasses over 30,000 species, with roughly 3,000 known in Ukraine. All of them feed on plant sap and possess piercing-sucking mouthparts, alongside two pairs of wings with similar venation, though the hindwings are smaller than the forewings or sometimes entirely absent. Scale insects and certain generations of aphids lack wings altogether (Fig. 386). In most species, body size ranges from 0.1 to several millimeters, with only a few cicadas reaching 6-8 cm.

This group includes cicadas with well-developed wings (Fig. 386, a, b). Males of many cicada species are capable of stridulation, with sound-producing and auditory organs located on the ventral surface of the metathorax. Nymphs live in the soil, feeding on the sap of roots or subterranean plant parts. Among them are several notable agricultural pests and vectors of crop Viruses. Several species of singing cicadas inhabit Crimea and the southern steppe regions of Ukraine, such as the European cicada (Lyristes plebeja), which grows up to 5 cm in length.

Psyllids are small insects, generally resembling cicadas in appearance, typically equipped with jumping legs. In spring, the apple sucker (Psylla mali) feeds on the sap of apple tree buds, causing them to wither. Like aphids, they produce honeydew.

Fig. 386. Hemipterans

(adapted from Gilyarov): a - common cicada (Lyristes plebeja); b - its larva; c, d - winged and wingless aphid females, respectively;

e - nettle scale insect (Orthezia urticae); f - colony of San Jose scale (Diaspidiotus perniciosus) on tree bark:

1 - female; 2 — male

Aphids are small, winged or wingless insects with very delicate integuments (Fig. 386, c, d). They exhibit complex reproductive cycles: parthenogenetic generations occur during the summer, while sexual reproduction takes place in autumn. Fertilized eggs, covered by a thick protective coat, overwinter. Aphids feed on the sap of above-ground and underground plant parts. Because of their extremely thin integuments, they lose a large amount of water through evaporation; consequently, they must ingest vast quantities of plant sap, excreting excess sugars unprocessed with their waste. These sweet secretions are known as "honeydew." They serve as a food source for many other insects, including ants, which protect aphids from predators (an example of mutualism). Many aphid species are serious agricultural pests. For instance, the grape phylloxera (Viteus vitifolii), introduced from America, causes massive destruction of vineyards. Other well-known orchard pests include the American woolly aphid and the green apple aphid, while the black bean aphid targets crops such as beets. Many aphid species secrete specific substances that induce pathological overgrowth of plant Tissues around the insect's body, forming galls.

Scale insects and mealybugs (Coccoidea) comprise two groups: mealybugs and armored scales. These are small insects exhibiting pronounced Sexual Dimorphism (Fig. 386, e, f). Males are winged, whereas females are wingless, often immobile, with reduced legs, and covered in waxy protective secretions forming scales or shields.

The oyster shell scale (Lepidosaphes ulmi), whose body is covered by a comma-shaped scale, is frequently found on apple tree branches. A highly dangerous fruit tree pest of East Asian origin—the San Jose scale (Diaspidiotus perniciosus), once introduced to North America—is now also found in southern Ukraine.

The protective secretions of certain coccid species serve as valuable industrial raw Materials. Some tropical species, such as Tachardia lacca, secrete a resinous substance called shellac, used for insulating fine electrical wires. The red dye carmine, utilized in the food and textile industries as well as in scientific research, is extracted from numerous species. In Ukraine, this substance is produced by the Polish cochineal (Margarodes polonicus). In China and Japan, wax for coating artistic handicrafts is obtained from the species Ericerus pela.

The order Hemiptera, or true bugs, comprises over 30,000 species, with more than 800 species found in Ukraine.

Their mouthparts are piercing-sucking, the antennae consist of three to five segments, the basal portion of the forewings is leathery with membranous tips, and the hindwings are also membranous and folded beneath the forewings (in some species, they are reduced, as shown in Fig. 387). A pair of thoracic scent glands secrete a repellent fluid containing cimicic acid as its primary component; these glands are reduced in aquatic and certain predatory forms.

Fig. 387. True bugs (adapted from Dogel):

a - forewing of a shield bug; b - bedbug (Cimex lectularius); c - sunn pest (Eurygaster integriceps):

1 - corium (hard part of the wing); 2 - membrane

Among true bugs, many are herbivorous forms that feed on plant sap. Particularly dangerous cereal pests include shield bugs (the sunn pest Eurygaster integriceps, E. maura, and E. austriacus). Predatory bugs (such as the family Reduviidae) hunt other insects, including agricultural pests. Some species have adapted to feed on the Blood of warm-blooded animals, including humans (Rhodnius, Triatoma). In tropical America, they act as specific vectors for Chagas disease, a severe illness caused by Trypanosoma cruzi. The bedbug (Cimex lectularius) is a well-known hematophagous species found in human dwellings worldwide. Numerous bug species have transitioned to an aquatic lifestyle in freshwater bodies. These are predominantly predatory insects that breathe atmospheric air. Among them, the backswimmer (Notonecta glauca), water scorpion (Nepa cinerea), and water stick insect (Ranatra linearis) are widely known.

The order Odonata (dragonflies and damselflies) unites about 5,000 extant species of highly specialized predators. Approximately 100 species are known in Ukraine.

Adults possess an elongated body, chewing mouthparts, two pairs of membranous wings, and large compound eyes. The antennae are short. Their Tibia and femora bear spines used to grasp and hold prey (Fig. 388). Adults hunt various insects on the wing, overpowering whatever they can catch. Flight is powered by pleural Muscles Attached to the base of each wing; each wing operates independently, ensuring exceptional flight maneuverability. This flight mechanism is unique to odonates.

Fig. 388. Odonates (from Dogel): a - hawker dragonfly (Aeschna), b - its larva

Females deposit their eggs in freshwater bodies. The larvae, known as naiads, are also predatory, capturing prey with their elongated lower lip (the "mask"). Their respiratory organs consist of tracheal gills, which are either arranged as three leaflet-like structures at the tip of the abdomen or located inside the hindgut. Ukraine is home to relatively small damselflies such as Lestes, Coenagrion, and Calopteryx, which fold their wings along the body at rest, as well as larger, brightly colored dragonflies like Cordulia and Aeschna, whose wings are held outstretched and cannot be folded. Several species are listed in the Red Data Book of Ukraine.

Insects with complete metamorphosis (Holometabola)

The order Coleoptera, or beetles, encompasses over 300,000 extant species. The exact number of beetle species in the fauna of Ukraine has yet to be fully determined, though it is estimated at around 15,000. Their sizes vary dramatically—ranging from 0.3 mm in featherwing beetles to 150 mm in the Hercules beetle.

Their mouthparts are of the chewing type. The forewings are modified into hard elytra that protect the second pair of membranous wings. In some ground-dwelling species (such as ground beetles and darkling beetles), the hindwings are reduced, rendering them flightless. Beetle legs are typically elongated and adapted for running; aquatic species feature swimming legs (diving beetles), soil-dwelling species have digging legs (dung beetles), and others possess jumping legs (leaf beetles) or clasping structures (male diving beetles). Larvae possess more or less developed thoracic legs, and more rarely are worm-like.

Many species feed on decaying wood (larvae of jewel beetles, longhorn beetles, etc.); they damage various bark layers of living trees (bark beetles), feed on green plant parts (leaf beetles, which include the Colorado potato beetle Leptinotarsa decemlineata — a well-known potato pest, bread beetles, weevils, the cockchafer Melolontha melolontha, etc.) or roots (larvae of click beetles and darkling beetles). A large group of beetles consume dung (dung beetles) or the remains of dead animals (carrion beetles). There are many predators (ground beetles, ladybirds, etc.) that feed on various invertebrates.

Fig. 389. Beetles:

a — Colorado potato beetle (Leptinotarsa decemlineata); b — its larva; c — great diving beetle (Dytiscus marginatus); d — its larva

Parasitic forms among beetles are quite rare: the larvae of blister beetles (Meloidae) and oil beetles parasitize in the nests of solitary bees, egg pods of grasshoppers, etc. The beaver beetle (Platypsyllus castoris) lives on the Eurasian beaver and feeds on its Skin scales.

Quite a few beetles live and develop in freshwater bodies. These include predatory diving beetles (Dytiscidae), which reach a length of 30-40 mm and hunt in the water Column, and small whirligig beetles (Gyrinidae), which circle on the water surface, diving for prey. The larvae of these beetles are predatory. Water scavenger beetles (Hydrophilidae) are also predominantly aquatic inhabitants; the adults are mostly herbivorous, while the larvae are predatory. In southern Ukraine lives the great silver water beetle (Hydrous piceus), which reaches a length of 50 mm.

Some beetles are listed in the Red Data Book of Ukraine, notably the largest species of our fauna — the stag beetle (Lucanus cervus), the males of which, together with their upper jaws, reach 75 mm in length. The larvae of this beetle develop in decaying wood for about five years and reach a length of 135 mm.

Order Neuroptera (Net-winged insects). About 5 thousand modern species are known, mostly tropical and subtropical forms. In Ukraine, there are 70-80 species.

This order unites insects with chewing mouthparts and two pairs of net-veined wings (Fig. 390). Adults feed on pollen and plant nectar or are predatory. The larvae are predatory; some of them crawl openly among clusters of prey (for example, larvae of green lacewings Chrysopidae among aphids), while others build trapping pits in the soil, where the predator hides at the bottom of such a pit and feeds on insects that fall into it (antlions (Myrmeleontidae), etc.). When pupating, the larvae secrete silk-like threads from the anus — a product of Malpighian tubule secretion — which form a cocoon.

Fig. 390. Net-winged insects (Neuroptera):

a — antlion Totateres sp., b — its larva

The rare species Ascalaphus macaronicus with brightly colored wings, distributed in Crimea, is listed in the Red Data Book of Ukraine. Some species are used in biological control against various aphid species (lacewings), including phylloxera (Osmylopa).

Order Trichoptera (Caddisflies) unites over 3 thousand species of medium-sized insects (0.5-4 cm). About 200 species are currently known in Ukraine.

Externally, adults resemble butterflies or moths. Elongated thread-like antennae, compound eyes, and three simple ocelli are located on the head. Upper jaws are absent. There is a short proboscis through which adults drink water, though they do not feed. Two pairs of membranous wings are covered with dense hairs (Fig. 391).

Fig. 391. Caddisflies (from Dogiel): a — adult Phryganea striata, b — larva of Limnophilus in its case

Females lay eggs in freshwater bodies. Larvae build protective cases from sand grains, small mollusk shells, pebbles, and plant

fragments. They glue these particles together with silk produced by silk-secreting (modified salivary) glands. Caddisfly larvae are predators; they feed on insect larvae, small crustaceans, etc., and, in turn, serve as good food for fish, such as trout.

Order Lepidoptera (Butterflies and Moths) is one of the richest in species (over 150 thousand) orders, uniting insects with a wingspan of 3 to 300 mm. The fauna of Ukraine counts up to 8 thousand species.

The mouthparts of adults are modified into a sucking proboscis. Two pairs of membranous wings are covered with scales of various shapes (Fig. 392). Scales can be pigmented or colorless; light diffraction occurs in the latter, which explains the iridescent (optical) coloration of the wings in many species. Adults feed mainly on flower nectar and are good pollinators; in some species, adults do not feed at all, such as in the silkworm moth.

Larvae (caterpillars) have chewing mouthparts, three pairs of thoracic legs, and two to five pairs of unjointed prolegs, with numerous cuticular hooks located at their tips. Salivary Glands secrete silk. Using silk, caterpillars can roll leaves into tubes, build silk nests, descend from branch to branch, etc. From silk, caterpillars of some species build a cocoon inside which they pupate. Most species in the larval stage are phytophagous. Some live in the soil, feeding on roots; the turnip moth (Agrotis segetum) causes the most damage. In many species, caterpillars lead an open lifestyle on food plants, for example, pests of cruciferous vegetables like the cabbage moth (Barathra brassicae) and the large white butterfly (Pieris brassicae). Many species damage orchards and forests. Caterpillars of such pests usually live in groups in silken nests (ermine moths (Hyponomeuta), gypsy moth (Lymantria dispar), etc.) or inside rolled leaves — some species of the leafroller family (Tortricidae). Caterpillars of certain species crawl significant distances in search of food, moving in column formation in regular rows, such as the pine processionary moth (Thaumetopoea processionea), which is frequently found in the Carpathian region.

Fig. 392. Silkworm (Bombyx mori) (from Pravdin): a — male; b — female; c — caterpillar; d — pupa; e — cocoon

Some phytophagous species live inside their nutritional substrate. For instance, the larvae of the codling moth (Laspeyresia pomonella) dwell inside apples, where they eat the seeds and tunnel through the flesh. The larvae of certain species form tunnels in wood, such as the goat moth (Cossus cossus), which has an unpleasant odor reminiscent of methyl alcohol. Leaf miners are caterpillars that excavate tunnels of various shapes within the chlorophyll-containing layer of leaves, such as the lilac leaf miner (Caloptilia syringella), etc.

The caterpillars of certain species inhabit aquatic environments. For instance, the brown china-mark (Nymphula nymphaeata) in its larval stage feeds on the leaves of water lilies and other aquatic plants. It constructs a portable, air-filled case from plant debris, much like caddisfly larvae. The caterpillars of other species feed on wool (the webbing clothes moth, Tineola bisseliella), honeycomb in beehives (the greater wax moth, Galleria mellonella), and various other substances of plant origin. In their larval stage, certain species adopt a predatory or even parasitic lifestyle.

For over 5,000 years, humans have cultivated the domesticated silkworm (Bombyx mori). Native to the Himalayas, it was eventually introduced to China, where sericulture began to flourish. Today, this species is cultured worldwide and no longer exists in the wild. Its primary food source is the mulberry tree, and the caterpillars are reared indoors in specialized facilities. When spinning its cocoon, a single caterpillar produces a silk thread about 2 km long. Silk is widely used in the textile industry, the manufacture of parachutes and airships, and in surgery for suturing wounds.

The vast majority of butterfly species are harmless. Some are utilized in biological control programs against ragweed and prickly pear cacti (Opuntia) in Australia. A great number of species—particularly certain groups of brightly colored butterflies—hold significant aesthetic and commercial value and are protected by law in various countries. The Red Data Book of Ukraine includes dozens of butterfly species, such as Apollo (Parnassius apollo), which inhabits the Crimean mountains, and the swallowtail (Papilio machaon), among others.

The order Diptera (true flies) comprises over 100,000 species and brings together insects of diverse sizes, ranging from 0.1 to 70 mm. In Ukraine, more than 4,000 species are known.

Adults (imagoes) possess well-developed compound eyes, one to three simple ocelli, and piercing-sucking or sponging mouthparts. The thoracic segments are completely fused; the forewings are membranous, while the hindwings are reduced and modified into club-shaped halteres, which serve as organs of equilibrium (Fig. 393).

The larvae are apodous (legless). In higher dipterans (flies), the head is completely reduced, mouthparts are modified into hooks, and extra-intestinal Digestion is well-developed. In lower dipterans (mosquitoes), the head is well-developed, featuring chewing-type mouthparts that are sometimes modified into filtering structures.

Nematocera (long-horned flies) have multi-segmented antennae and larvae with a more or less developed head capsule (e.g., blackflies, sandflies, mosquitoes). Brachycera (short-horned flies), characterized by three-segmented antennae and headless larvae, include true flies, horse flies, botflies, and others. In most brachycerans, the larva pupates inside its own larval skin, which hardens to form an additional protective casing known as a puparium.

The larvae of many nematocerans (blackflies (Simuliidae), blood-feeding mosquitoes (Culicidae), non-biting midges (Chironomidae)) inhabit freshwater bodies, where they feed as filter feeders or detritivores, and more rarely as predators (such as Corethra, family Chaoboridae). Certain fly larvae, like Eristalis, also inhabit aquatic environments. They feature a telescopic respiratory tube at the posterior end equipped with spiracles, allowing them to breathe atmospheric air. All these forms, particularly the larvae of non-biting midges of the family Chironomidae, are widely known as "bloodworms" and serve as a crucial component of the fish diet.

In their larval stage, brachyceran flies feed on PLANT AND ANIMAL remains, playing an exceptionally vital role in soil humification. Some of them—predominantly members of the house fly family (Muscidae) like the house fly (Musca domestica), green blowflies (Lucilia) and blue bottle flies (Calliphora) of the family Calliphoridae, as well as flesh flies (family Sarcophagidae)—have adapted to decomposing organic matter (such as garbage dumps and outdoor toilets) in human settlements, forming an important component of the synanthropic insect complex.

Fig. 393. Diptera:

a – female malaria mosquito Anopheles maculipennis during blood-feeding; b – its larva; c – robber fly Philonicus; d – hoverfly Syrphus

Herbivorous dipteran larvae lead a predominantly concealed lifestyle within galls (gall midges (Cecidomyiidae)), as leaf miners (some species of frit flies and other Chloropidae), or inside stems, inflorescences, or fruits (for example, the larva of the frit fly (Oscinella frit) damages spikelet primordia or the grains of wheat, rye, and other cereals).

Among dipteran larvae, predators are very common. The larvae of certain species, such as horseflies (Tabanidae) and robber flies (Asilidae), live in the soil and leaf litter where they prey on various invertebrates; others inhabit decaying carcasses, feeding mainly on insect larvae. The larvae of many species from the families Leucomyidae and hoverflies (Syrphidae) are specialized predators of aphids, scale insects, and other small hemipterans, and are utilized in the biological control of these pests.

Parasitism is also widespread among dipteran larvae; for instance, tachinid fly larvae (Tachinidae) are parasites of other insects, including harmful ones. Warble fly larvae parasitize the subcutaneous tissues, nasopharyngeal cavities, Stomach, and intestines of various domestic animals, causing significant economic loss to livestock farming. The larvae of the Wohlfahrt fly (Wolfahrtia magnifica) pose a severe threat to sheep farming in southern Ukraine. They develop in wounds and chafed areas, eating away the Muscle tissue down to the bone. Cases of infestation in other animals and humans are also known.

Adult dipterans feed primarily on pollen and flower nectar, and many species are effective pollinators. Blood-sucking forms are also common. In females of blood-sucking nematocerans and horseflies, the urge to feed on blood arises after fertilization, as blood is essential for egg development. Males of these insect groups do not consume blood. Among stable flies (Stomoxis) and tsetse flies (Glossina), both sexes are blood-suckers. The complex of blood-sucking insects is collectively known as "gnat" (or blood-sucking flies). Most of them act as vectors for dangerous diseases. Certain groups of blood-sucking dipterans have shifted to ectoparasitism, with some having lost their wings, such as the sheep ked (Melophagus ovinus). Finally, adult botflies do not feed at all; they live for a short time utilizing fat body reserves and die after oviposition.

Some dipterans, such as the giant robber fly (Satanas gigas), which reaches a length of 5 cm, are listed in the Red Data Book of Ukraine.

The order Fleas (Aphaniptera) comprises over 2,000 species of wingless blood-sucking insects, with about 60 species found in Ukraine.

Their body is laterally compressed, measuring 1–6 mm in length. The head bears short antennae, a pair of simple eyes (sometimes absent), and a piercing-sucking mouthparts. The body is adapted for rapid movement through the fur or plumage of mammals and birds. The legs are jumping-type (Fig. 394). Adults feed exclusively on blood and are host-specific. The human flea (Pulex irritans) feeds on human blood. Certain rodent-associated flea species are vectors of plague, while others, predominantly tropical, parasitize the skin of animals and humans. Flea larvae are worm-like, inhabit floor cracks, bedding in burrows or nests, and feed on organic debris.

Fig. 394. Fleas (after Dogiel):

a - human flea Pulex irritans; b - its larva; c - pupa

The order Hymenoptera includes about 200,000 species, with approximately 30,000 species known in Ukraine. Body sizes range from fractions of a millimeter to 6 cm.

These are insects with two pairs of membranous wings, the hind wings being smaller than the fore wings. Mouthparts are biting-lapping or biting-sucking, with the lower lip modified into a proboscis (Figs. 395–397). Hymenopterans are divided into two sharply distinct suborders: Symphyta (sawflies, woodwasps, and horntails) and Apocrita (wasps, ants, and bees).

Symphyta are characterized by an abdomen with a broad base attached directly to the thorax (Fig. 395, a, b). The larvae possess biting mouthparts, thoracic legs (in woodwasps) or thoracic legs plus six to eight pairs of abdominal prolegs (in sawflies). Larvae are phytophagous; in sawflies (Tenthredinidae), they damage green plant parts (e.g., the pine sawfly - Diprion pini) and are commonly called false caterpillars (or slugs), whereas in horntails (Siricoidea), the larvae bore into the wood of conifers and angiosperms.

In Apocrita, the first abdominal segment is fused with the thorax, while the second forms a narrow petiole, followed by the expanded part of the abdomen (Fig. 396, c–e). The larvae are legless. They typically feed on insects and spiders through predation and parasitism, and occasionally secondary phytophagy.

Fig. 395. Hymenopterans (from Dlussky): a — European pine sawfly (Diprion pini); b — its larva; c — parasitic wasp (Trichogramma evanescens) on a butterfly egg; d — parasitic wasp (Megarhyssa emarginatoria) ovipositing into the larva of a wood-boring horntail; e — potter wasp (Eumenes) carrying prey to its pot-shaped nest

The term "parasitic wasps" (or parasitoids) encompasses A large number of families whose larvae parasitize various Developmental Stages of insects, from eggs to adults. Among them, egg parasitoids of the genus Trichogramma are used to control the codling moth and other harmful Lepidoptera. Apanteles juliuipes parasitizes gypsy moth caterpillars, while Aphelinus mali targets adult woolly apple aphids. Some parasitic wasps induce plant galls (gall wasps, family Cynipidae). For instance, the "oak apples" on oak leaves—historically used to manufacture black ink—are formed by the oak gall wasp (Cynips quercusfolii).

Within the Apocrita, a distinct group is known as the Aculeata (stinging wasps): in females, the ovipositor is modified into a sting connected to the ducts of venom glands. This group includes wasps, bees, and ants.

Sphecid wasps (family Sphecidae) immobilize various insects and spiders by stinging their nerve centers, transport them to specialized nests, and lay eggs on the paralyzed prey. The wasp then seals and disguises the nest. The emerging larvae feed on these unique "living preserves." For example, Ammophila paralyzes cutworm caterpillars, while Sceliphron targets spiders. Cuckoo wasps (family Chrysididae), featuring striking metallic coloration, lay their eggs in the nests of digger wasps; their larvae consume both the host larva and its provisions—paralyzed Arthropods. Scoliid wasps (family Scoliidae) sting the ventral nerve center of large rhinoceros beetle larvae (Oryctes nasicornis), paralyzing them. Immediately afterward, the female lays an egg, from which a larva emerges to consume the immobilized victim.

Among the stinging Hymenoptera, many are social insects. Vespid wasps (family Vespidae) construct nests from wood fibers chewed with mandibles and mixed with saliva, producing a paper-like material. Adults feed on nectar and other sugary substances, while provisioning their larvae with chewed-up insects. The hornet (Vespa crabro), the largest representative of this family in Ukraine, reaches up to 3 cm in length. Hornet stings are hazardous to human life, and near apiaries, they cause damage by killing large numbers of worker bees. Near human settlements, however, Vespidae are generally beneficial because they destroy synanthropic flies.

The superfamily Apoidea comprises six families and includes about 30,000 species. These are specialized Hymenoptera that feed on flower nectar and pollen, with their hind legs modified into pollen-collecting apparatuses. They include both solitary and social species. Females of solitary species independently build nests with comb Cells, care for their offspring, and gather honey and pollen. In social bees, alongside males and females, there are worker castes (sterile females) that perform construction work, gather nectar and pollen, and rear the brood. Such bee species are polymorphic, exhibiting complex social interactions and division of labor within their colonies. Social bees include the honeybee (Apis mellifera) (Fig. 396) and bumblebees (genus Bombus). Several bee species are cultivated by humans for honey, wax, and propolis.

Fig. 396. Honeybee (Apis mellifera) (from Natali): a — queen; b — worker bee; c — drone

All species of the ant family (Formicidae), numbering over 10,000, are social insects. Worker individuals are always wingless and often form distinct castes. For instance, in Messor clivorum, a species widespread in the steppes of Ukraine, there are soldiers with exceptionally large heads and mandibles alongside smaller workers with normal mandibles. Ant nests are located in the soil or tree hollows. Oecophylla smaragdina, widely used in Southeast Asia for orchard pest control, builds its nests among tree leaves. Workers pull the edges of leaves together and bring larvae toward them; the larvae produce a sticky secretion from their salivary glands that glues the leaves together.

Most ants are predatory. The red wood ant (Formica rufa) is common in Ukraine; it and its close relatives eradicate vast numbers of forest insect pests. In South America, army ants of the genus Eciton form colonies numbering many millions of individuals. They do not build permanent nests and spend most of their lives on the move, devouring not only invertebrates but also small vertebrates such as amphibians, reptiles, and mammals along their path.

A significant number of ant species are phytophagous. Harvester ants of the genus Messor collect and store cereal grains in their nests. Tropical leaf-cutter ants of the genus Atta carry pieces of green foliage to underground chambers, where they cultivate specialized fungi on which they feed.

Most ants consume aphid honeydew as a source of CARBOHYDRATES. The black garden ant (Lasius niger) protects and tends pest aphid species in gardens and parks. The synanthropic Pharaoh ant (Monomorium pharaonis) lives in human dwellings, where it damages food products; it was originally introduced from the tropics.

Fig. 397. Red wood ant (Formica rufa)

A unique phenomenon of social parasitism is known exclusively among ants. The Amazon ant (Polyergus rufescens) inhabits the steppes and forest-steppes of Ukraine. A fertilized female infiltrates a nest of Formica fusca, kills the resident queen, and takes her place. The slave ants rear the brood of their masters, forage for the entire colony, and feed the adult Polyergus, as the latter are incapable of feeding themselves. When the slave population dwindles, the Amazons march in columns on slave-raiding expeditions to other colonies, capturing pupae and bringing them back to their nest. The slaves emerging from these pupae treat the Amazon nest as their own and perform all labor related to brood care, nest maintenance, and foraging.

Insects play a critically important role in terrestrial and freshwater biocenoses due to their sheer Abundance, biomass, and trophic diversity. Their contribution to biogeochemical nutrient cycling is immense. They occupy various links in food webs, consuming virtually any organic substrate of plant or animal origin, while many act as predators and parasites. In turn, insects serve as a vital food source for numerous invertebrates and vertebrates.

The vast majority of insects (about 80%) are phytophagous, feeding on living plants or plant remains. These include representatives of orders such as Orthoptera, Hemiptera, Coleoptera, Lepidoptera, certain Hymenoptera, and many Diptera. Insects consume all vegetative and generative plant organs: leaves, herbaceous stems and wood, underground structures, flowers, pollen, Ovaries, fruits, and seeds. Many insect larvae—such as those of fungus gnats, click beetles, longhorn beetles, darkling beetles, and bark beetles—feed on the fruiting bodies of agaric fungi and the mycelium of Molds developing in soil, leaf litter, and decaying wood. Numerous termite species and leaf-cutter ants (genus Atta) cultivate specific fungi in their nests, consuming their fruiting bodies. Other insects and their larvae feed on feces, dung, and manure (coprophages), including dung beetles, larvae of many brachyceran flies, and others. Carcasses of vertebrates and invertebrates are consumed by necrophages, such as sexton beetles and brachyceran fly larvae. Insects that consume decaying organic matter and soil fungi, as well as those that build nests underground (ants, termites), play a crucial role in pedogenesis (soil formation) by enriching the soil with humus and aerating it.

Predatory and parasitic insects act as natural regulators keeping the population densities of their prey and hosts in check. A similar regulatory role is played by vertebrate parasites and blood-feeders, which furthermore frequently vector disease pathogens (lice, bed bugs and blood-sucking Diptera, fleas, and others).

Insects play a colossal role in the pollination of flowering plants. Most angiosperms are entomophilous, meaning they are pollinated by insects. The mutual adaptations between insects and flowering plants for entomophily evolved through co-Evolutionary Processes starting with the emergence of flowering plants in the mid-Cretaceous. The primary groups of pollinators are nectar- and pollen-feeders: bees and bumblebees among Hymenoptera, most butterflies and flies, and certain beetles.

Insects are also of great significance to humanity and agriculture. They pollinate a vast number of cultivated plant species, most notably nearly all fruit trees and berry bushes, as well as legumes, crucifers, and many others. Certain plants cannot reproduce at all without specialized pollinators. For instance, high-yielding clover introduced to New Zealand failed to produce seeds until bumblebees—its specialized pollinators—were imported there.

Since ancient times, humans have bred specific insect species to obtain valuable products. Foremost among these is the honeybee (Apis mellifera), which yields honey, propolis, bee bread, royal jelly, and wax. Sericulture—the breeding of the silkworm (Bombyx mori) for natural silk—is a major branch of national economy in many countries.

Humans also utilize other insect-derived products. Carmine is a red dye obtained from certain scale insects: in Europe, from the Polish cochineal (Porphyrophora polonica), and in the Americas, from the cochineal bug (Coccus cacti). Shellac is a valuable industrial resin secreted by the lac insect (Laccifer lacca), used as an ultra-thin insulating coating in electrical engineering, medicine, and sound recording.

Insects are of major importance in agriculture and forestry due to The Development of biological pest control Methods. This approach utilizes predatory and parasitic insects known as entomophages. Certain species (such as parasitic wasps, digger wasps, predatory bugs and beetles, and lacewings) are intentionally acclimatized or mass-reared in biolaboratories and released into orchards, vegetable gardens, and crop fields.

The Use of insects for Processing livestock waste is highly effective. Most commonly, two species of coprophagous flies—Musca domestica and Protophormia terraenovae—are utilized to process pig manure and chicken droppings. The offspring of a single pair of these flies yield a biomass of 625 and 1.8 thousand tons, respectively. This biological waste processing yields both a valuable feed product rich in animal proteins and an excellent fertilizer. Meal derived from fly larvae is successfully used as a feed additive in animal husbandry.

Insects are exceptionally convenient subjects for a wide range of scientific research in biology, ecology, genetics, physiology, toxicology, biochemistry, and biophysics. This is due to their ease of breeding, low maintenance, and short life cycles. Since the early 20th century to the present day, the fruit fly Drosophila melanogaster has served as a pivotal model Organism for classical genetic research.

At the same time, many phytophagous insect species damage cultivated plants, causing severe economic losses, particularly in agriculture. Tens of thousands of pest species devastate crop fields and damage trees in orchards and forests. Periodic mass outbreaks of insect pests—typical of locusts, certain aphids, butterflies, beetles, and other groups—pose a particularly severe threat.

A distinct group consists of insects that infest food raw materials of both plant and animal origin. Granary weevils, powderpost beetles, grain moths, mealworms, and grain beetles spoil grain, flour, groats, grass seeds, plant and herbal raw materials, and bakery products. Dermestid beetles damage hides, furs, silkworm cocoons, and meat products; fur moths infest furs, fabrics, and products made from natural and occasionally synthetic materials.

Numerous insects are parasites of animals and humans. Ectoparasites of humans and mammals include blood-sucking insects such as fleas, lice, certain true bugs, and various Diptera (biting midges and flies): mosquitoes, blackflies, sandflies, biting midges, and horseflies. Beyond the irritation caused by their bites, these insects vector dangerous pathogens (pathogenic bacteria, viruses, Protozoa, and even parasitic worms). However, some disease vectors are not strictly parasites; for instance, the housefly mechanically transmits the causative agents of human intestinal infections on its body.

Some insects also act as endoparasites of mammals during their larval stage. These include botflies and certain other flies (such as the Wohlfahrtia fly), whose larvae parasitize domestic animals (sheep, horses, cattle), causing substantial economic losses to livestock farming.