The following points highlight the thirty-six representative types of Arthropoda found in the world. Some of the types are: 1. Limulus 2. Spider 3. Aranea 4. Mites 5. Sarcoptes 6. Ixodes 7.Apus 8. Daphnia 9. Cypris 10. Cyclops 11. Lepas 12. Balanus 13. Sacculina 14. Mysis 15. Oniscus 16. Squilla 17. Hippa 18. Eupagurus 19. Cancer (Crab) 20. Julus 21. Scolopendra 22. Lepisma and Others.
Arthropoda: Type # 1. Limulus:
Limulus (Fig. 81.1) is commonly known as king crab. Body consists of anterior prosoma and a posterior opisthosoma.
Prosoma is convex above with sloping sides and bears three longitudinal ridges, one median and two lateral. A pair of simple median eyes and pair of lateral compound eyes are placed on the dorsal surface of prosoma. Prosoma bears six pairs of appendages grouped round the mouth, the first pair of chelate chelicerae, four pairs of chelate legs and a last pair of non-chelate legs.
Opisthosoma is hexagonal, movably articulated with prosoma and consists of six mesosomal segments and un-segmented metasoma with long telson or caudal spines. Opisthosoma bears six pairs of appendages, first pair forms genital operculum, the remaining five pairs carry book lungs. Respiration by book gills. Excretion by coxal or brick red glands. Larva is trilobite. Limulus is a marine form found burrowing in the sand.
Arthropoda: Type # 2. Spiders:
Spiders (Fig. 81.2) are the most successful Arachnida and about 35,000 species are known. Spiders have two characteristic adaptations, first they produce silk for a variety of uses and second the pedipalpi of males are modified to form copulatory organs.
Body is divided into two regions, a prosoma and an opisthosoma, the two are joined by a narrow waist or pedicel, the body and limbs are thickly covered with chitinous hairs which are probably tactile. Prosoma is covered dorsally by a carapace formed by fused terga of 6 segments and ventrally by a sternum.
Mid-dorsally the carapace has 4 pairs of simple eyes, the region of carapace in front of the eyes is a clypeus, posteriorly the carapace has a series of depressions. In front of the sternum is a labium, the upper lip is called a rostrum, between the lips is a small mouth.
Prosoma bears 6 pairs of appendages, a pair of 2- jointed chelicerae lying in front and above the mouth, each consists of a large basal segment, the paturon which contains a poison gland and a laijg-like distal segment, the unguis at whose tip the duct of the poison gland opens.
There is a pair of 6 jointed pedipalpi which are non-chelate and their basal joint forms a gnathobase; the joints are coxa, trochanter, femur, patella, tibia and tarsus.
The pedipalp of a male spider is modified to form an intromittent organ lying in the tarsus and consisting of a bulb having seminal vesicle and a spirally-twisted tube through which spermatozoa are transferred to the female during copulation.
There are 4 pairs of 7-jointed legs, the joints are coxa, trochanter, femur, patella, tibia, metatarsus and tarsus; the tarsus usually has 2 claws. Opisthosoma is soft and usually unsegfneriied but is made of 13 segments.
The first or pre-genital segment forms the pedicel, its tergum is called lorum and sternum, the plagula. The second segment has the first pair of lung books, it also has a single genital aperture. The third segment bears either a second pair of lung books or a pair of spiracles.
Fourth segment has an anterior pair of spinnerets and the fifth segment has one or two pairs of spinnerets, over the spinnerets is often a special cover called cribellum. The remaining opisthosomatic segments are limbless, they are fused together to form a small anal tubercle at the end of which opens an anus.
The base of each spinneret is firm but the tip is membranous having hairs and barbs; these form a spinning field. Spider have either 2 pairs or 3 pairs of spinnerets which form a spinning apparatus or arachnidium. Inside the opisthosoma are spinning or silk glands from which fine tubes open on the surface of the spinning field of the spinnerets; the secretion of glands issues through the tubes and forms silk threads.
The silk is used for lining the burrows or nests or it is used for making a cocoon for the eggs or for wrapping the captured prey, or it is formed into a safety line by which the spider can hang in mid air, or in some spiders it is used for spinning a web for snaring the prey.
In some spiders there are special curved spines called calamistrum on the tarsus of hind legs which are used in conjunction with spinnerets for weaving the silk into a web. Respiratory organs consist of lung book and tracheae, their number varies in different groups of spiders, both have external openings or spiracles.
In most spiders there is a pair of lung books and a pair of spiracles leading into straight, un-branched tracheae. Some spiders have two pairs of lung books, while others have only two pairs of spiracles with tracheae. Thus, spiders show all stages of replacement of lung books by tracheae.
Spiders are carnivorous feeding on insects, but some on larger animals also. The prey is killed by the poison in chelicerae, proteolytic enzymes are produced by salivary glands of lips which cause partial external digestion, liquid food is strained by bristles and sucked in by pulsations of the stomach, the chitinous remains of the prey are discarded as empty husk.
The mid-gut has several diverticula, a main diverticulum in opisthosoma, and one pair in prosoma which send a branch into each leg. Food is stored and digestion is completed in the diverticula.
Sexes are separate with sexual dimorphism in many, the male being smaller than the female. The male sucks up spermatozoa into its pedipalpi then courtship and copulation follow. In some spiders the female eats the male after copulation. Fertilised eggs are enclosed in a cocoon spun by spinnerets.
Arthropoda: Type # 3. Aranea (Spider):
Aranea (Fig. 81.4) is commonly known as orb webbed spider. Body consists of prosoma and an opisthosoma, the two being connected by a narrow pedicel. Prosoma is covered by carapace and bears eight eyes dorsally and six pairs of appendages. Chelicerae are sub-chelate and contain poison glands. Pedipalpi are simple and six jointed.
Opisthosoma is un-segmented, bears three pairs of spinnerets which produce threads for making webs. Respiration by book-lung and tracheae. Excretion by Malpighian tubules and coxal glands. Sexes are separate, sexual dimorphism is often well marked. Carnivorous. Aranea is found in houses and gardens.
Arthropoda: Type # 4. Mites:
Mites surpass all other arachnids in numbers, they are minute microscopic Acarina. The free-living mites feed on animal and vegetable matter, they are found on the ground, under dead leaves or bark and on plants on which some species form galls. Many mites are terrestrial and some are aquatic but they have no gills.
About 50 per cent of mites are parasitic, they infect almost all kinds of animals, they are mostly ectoparasites of man and animals, though a few are endoparasites, e.g., Pneumonyssus in lungs of monkeys. In mites the prosoma and opisthosoma are un-segmented having no division, they are so joined as to form a single ovoid body, though in some it may be elongate.
The body is covered with tactile hairs or scales. Eyes may be present or absent. There are 6 pairs of appendages, chelicerae are chelate or modified for piercing and sucking, pedipalpi are leg-like with 5 joints or less, their basal joint may form a plate called mascilla or may unite to form a labium.
Accessory mouth partsare often present as a hypostome or under lip and an epistome or upper lip, the lips may unite to form a rostrum enclosing protruding chelicerae. The chelicerae open an incision and the hypostome penetrates and liquids are sucked in. There are generally four pairs of legs.
Respiratory organs are absent or there are tracheae. Sexes are separate, the young hatches as a larva with three pairs of legs, it feeds and rests, then moults to form a nymph with four pairs of legs, there may be up to three nymphal stages the final moulting produces an adult.
Some common mites are described. Eriophyes is a gall mite it kills buds, causes leaf curl and makes large abnormal galls on twigs. Demodex is a follicle mite, it has an elongated body, it lives in sebaceous glands and hair follicles of man and animals and causes dermatitis.
Arthropoda: Type # 5. Sarcoptes:
Sarcoptes (Fig. 81.5) is minute in size and microscopic. Body is oval or rounded and dorsoventrally flattened having transverse striations and few short bristles. Mouth parts are situated anteriorly and provided with chelate chelicerae. Four pairs of legs. Anterior two legs are stronger and project beyond the body and provided with terminal stalked suckers.
Posterior two legs are shorter and attached more ventrally and carry long bristles. Prosoma and opisthosoma are not distinguishable. Sarcoptes scabiei is an unpleasant dangerous ectoparasite which attacks man causing scabies which produce severe irritation that may lead to eczema. The parasite bores down and lives below the skin especially in soft regions.
Ticks are large mites with leathery skin, all of them feed on vertebrate blood, they have several distensible diverticula of the gut which are filled up with blood.
Their saliva contains an anticoagulin, as in leeches, which prevents coagulation of blood. Ticks are of two types, soft-bodied ticks without a scutum but a ventral capitulum (Argasidae) and hard- bodied ticks with dorsal shield or scutum and dorsal capitulum (Ixodidae).
The scutum nearly covers the entire dorsal surface in males, but in females it is much smaller. They have a movable capitulum having a rostrum enclosing toothed chelicerae and toothed hypostome, pedipalpi are 3 or 4-jointed. There are 4 pairs of prominent, slender 6-jointed legs with two claws and a pad or pulvillus. They are parasites of mammals, birds and reptiles.
Arthropoda: Type # 6. Ixodes (Sheep Tick):
It is brown in colour and 4 mm long. There is no division into prosoma and opisthosoma. Anteriorly is an oval, movable false head or capitulum behind which is a body covered with leathery skin with no sign of segmentation. Capitulum has two sensory pitted areas dorsally in the female only, there are no eyes.
The sternal region of capitulum is elongated in front to form a hypostome having many recurved hooks and a mid-dorsal groove. On each side of the hypostome is a two- jointed chelicera toothed at the tip. A pair of 4-jointed pedipalpi have their basal joints united to form a sheath which encloses the chelicerae and hypostome, thus, forming a bloodsucking apparatus.
There are four pairs of slender legs, the legs are 7-jointed ending in two claws and sucker-like pulvillus. The tarsus of first pair of legs has a sensory cup-shaped Haller’s organ. The body behind the capitulum is covered by a dorsal, chitinous scutum or dorsal shield, completely in the male, but only in the anterior half in the female, because of this the body of the female can be distended greatly on feeding.
At the posterior ventral side is an anus. Behind the fourth pair of legs is a pair of prominent spiracles leading into convoluted tracheae. Between the first and second pairs of legs is a single genital aperture.
The female, after gorging itself with blood of sheep, copulates with a male, then drops to the ground. The male feeds after copulation. After weeks the female lays eggs near roots of grass, eggs hatch into larvae with three pairs of legs. Larvae climb upon grass and cling to any vertebrate and suck blood.
After feeding for 3 or 4 days they fall off and moult to become nymphs with 4 pairs of legs. Nymphs climb up a new vertebrate host and suck blood for 5 days, then they fall to the ground and moult to become adult which find a new host. The larvae, nymphs, and adults can live without food for months.
Ixodes is a sheep tick, it transmits a virus which causes tick fever in sheep and domestic animals and it also causes encephalitis in man. Argas is a poultry tick, it carries a spirochaete which causes relapsing fever in poultry. It also bites man.
Margaropus or Boophilus is a cattle tick, it inoculates Babesia bigemina, a sporozoan, into the blood which causes Texas fever in cattle which proves fatal. Dermacentor is a dog tick of brown colour, parasitic on domestic animals and man, it causes a dangerous tularemia and relapsing fever. Ornithodorus transmits a spirochaete Rickettsia which causes dangerous relapsing fever in man.
Arthropoda: Type # 7. Apus:
Apus (Fig. 81.7) is commonly known as tadpole fish. Body is elongated measuring about 20-30 mm in length. Anterior two-third of the dorsal surface is covered by a horse-shoe- shaped carapace. Head is broad and depressed and bears paired eyes, a median eye and a dorsal organ above and antennules and antennae below.
Shell glands are present on the lateral surface of carapace. Anal segment bears a pair of caudal styles. Reproduction by parthenogenesis. Apus is found in freshwater in most part of the world.
Arthropoda: Type # 8. Daphnia:
Daphnia (Fig. 81.8) is commonly called water flea. Body is soft, laterally compressed measuring 1-2 mm in length. Segmentation is very imperfect. Carapace ends into a pointed dorsal spine. Head is rounded and bears a pair of large biramous antennae, a pair of small antennules and a compound sessile eye. Large biramous antennae are the chief organs of locomotion.
Thorax bears usually five pairs of leaf-like appendages. Abdomen is devoid of appendages. Sexes are separate. Female carries eggs and embryos in a large brood pouch situated between abdomen and posterior part of the carapace. Daphnia is found in freshwater ponds, streams and ditches.
Arthropoda: Type # 9. Cypris:
Body is un-segmented and laterally compressed. The body is completely enclosed in a bivalved carapace. At the anterior end is a median eye. antennule Compound eye and heart are absent. There are only seven pairs of appendages, i.e., antennules, antennae, mandibles, first maxilla, second maxilla and two pairs of thoracic appendages.
Antennules and antennae are large biramous and help in swimming. Abdomen is devoid of appendages and is terminated by a pair of small caudal styles. Development by parthenogenesis. Cypris is free swimming and occurs in freshwater stagnant ponds.
Arthropoda: Type # 10. Cyclops:
Body is elongated or pear-shaped measuring 1.5 to 5 mm in length. First thoracic segment is fused with the head forming the cephalothorax which is covered dorsally by carapace. Single median eye is present on the dorsal surface of the carapace. Five pairs, of thoracic segments, last segment bears the genital aperture.
Four abdominal segments, last segment bears, the anus dorsally and a pair of caudal styles produced into plummed setae. Antennules are very large and serve as principal organs of locomotion. Antennae are relatively short and uniramous.
Abdomen is devoid of appendages except the caudal styles. Sexes are separate. Mature females carry two egg-sacs attached to the abdomen. Cyclops is a free swimming copepod found everywhere in fresh and brackish water.
Arthropoda: Type # 11. Lepas:
Lepas (Fig. 81.11) is commonly known as goose barnacle or ship barnacle. Body consists of a long stalk or pedicel and capitulum (the body proper).
Pedicel is covered with a wrinkled skin and bears the body proper at its distal end. Capitulum is enclosed in a bivalved carapace strengthened by five calcareous plates, two proximal scuta, two distal terga and a single dorsal carina. Mouth is provided with a pair of mandibles and two pairs of maxillae.
Antennae and paired eyes are absent. Thorax bears six pairs of many jointed biramous appendages fringed with tufts of setae. Hermaphrodite, i.e., sexes united. Lepas feeds upon minute organisms gathered by the threadlike feet and are wafted into the mouth. Lepas is sessile in habit and found all over the world attached to the floating objects.
Arthropoda: Type # 12. Balanus:
Balanus (Fig. 81.12) is commonly known as rock barnacle or acorn barnacle. Peduncle is absent so the shell is directly attached to the rocks. Body is surrounded by a calcareous shell comprising of six plates, an unpaired carina, an unpaired rostrum and two pairs of lateral plates.
The opening of the shell is provided with a fourfold cover consisting of two scuta and twoterga. Six pairs of thoracic legs are protruded out through the opening of shell and sweep in food particles. Hermaphrodite, i.e., sexes united. Larva is nauplius. Balanus is found attached to rocks below high water mark.
Arthropoda: Type # 13. Sacculina:
Sacculina (Fig. 81.13) is commonly known as root headed barnacle. It has the appearance of a fleshy tumour attached by a peduncle to the abdomen of the crab on its ventral side. It shows extreme degeneration due to parasitic mode of life. Segmentation, appendages, mouth and anus are entirely absent. Peduncle sends numerous delicate root like filaments which ramify within body of the host and absorb nourishment.
Opening of the mantle cavity is placed at the hind end of the parasite. Hermaphrodite, i.e., sexes are united. Larva is cirripedenauplius. Sacculina causes many changes in the secondary sexual characters of the host, a phenomenon known as parasitic castration. Sacculina is found as parasite on crabs.
Arthropoda: Type # 14. Mysis:
Mysis (Fig. 81.14) is a small transparent shrimp-like form. Body is bilaterally compressed and elongated measuring from 2-6 mm in length. Carapace covers the entire thorax except the last two segments. Head bears antennules, antennae and a pair of stalked eyes.
First pair of thoracic appendages are modified as maxillipedes and the rest are biramous serving as swimming organs. Brood pouch is attached to the posterior thoracic segments. Development takes place within the brood pouch, so there is no larval stage. Mysis is a marine pelagic form. It is generally confined to the surface of water.
Arthropoda: Type # 15. Oniscus:
Oniscus (Fig. 81.15) is commonly known as wood louse or sow bug. Body is broad, oval and dorso-ventrally flattened. Head is fused with the first segment of the thorax forming the cephalothorax which is not covered dorsally by carapace. Eyes are sessile and compound. Antennules and antennae are uniramous. It feeds upon decaying vegetation. Oniscus is a terrestrial crustacean found under stones logs and bark, etc.
Arthropoda: Type # 16. Squilla:
Body of Squilla (Fig. 81.16) is elongated measuring up to 25 mm in length and divisible into head, thorax and broad abdomen. Carapace is thin and un-calcified which leaves the last three segments uncovered.
Rostrum covers the anterior head region which is divided into two distinct segments, the first bearing the stalked eyes and the second the antennules. First five pairs of thoracic appendages are turned forwards and act as maxillipedes of which the second pair is exceptionally large and sub-chelate. Remaining three thoracic appendages are slender legs.
Pleopods are large and biramous, first five bear gills, the sixth forms large uropod. Squilla is active and predatory, it catches hold of the prey with the powerful maxillipedes. It is found in burrows in the sand or mud at the bottom of the sea.
Arthropoda: Type # 17. Hippa:
Hippa or Emerita (Fig. 81.17) is commonly known as mole crab. Body is ovate with large cephalothorax. Carapace is smooth and mouth parts are poorly developed. Head bears eyes, a pair of biramous antennules and a pair of uniramous large antennae.
Rostrum is simple and pointed. Legs are flattened and curved and are used in burrowing. It is said that it feeds like an earthworm swallowing the sand through which it burrows. Hippa lives in burrows in sand in the sea.
Arthropoda: Type # 18. Eupagurus:
Eupagurus (Fig. 81.18) is commonly known as hermit crab. Body is elongated, asymmetrical and consists of cephalothorax and abdomen. Cephalothorax is broad and flattened. Head bears a pair of stalked elongated eyes, a pair of short antennules and a pair of large antennae. Thorax bears five pairs of legs, the first pair of chelate legs having unequal chelae, the last two pairs are usually reduced.
Abdomen is soft, contains liver and gonads and spirally twisted to suit the shape of the shell. Abdominal appendages of the right side are absent, while those of the left side are reduced. Last pair of abdominal appendages or uropods are hook-like and are adapted to cling the shell. Eupagurus is found inhabiting the empty shells of gastropods.
Arthropoda: Type # 19. Cancer (Crab):
Cancer (Fig. 81.19) is commonly known as rock crab or true crab. Body is oval and flattened. Cephalothorax is frequently much broader than long. Eye stalks and antennules are continued in sockets of carapace. Antennules and antennae are small. Third maxillipedes are broad, flat and valve-like and cover the other mouth parts. Five pairs of thoracic legs are well developed. The first pair of legs is chelate.
Abdomen is greatly reduced and lies permanently flexed in a groove on the very broad thoracic sterna. Pleopods are much reduced, the male retaining only two pairs as copulatory organs, while female four pairs for attachment of the eggs. Uropods are absent. Cancer is found buried among rocks or in sand.
Arthropoda: Type # 20. Julus;
Body of julus (Fig. 81.20) is elongated and cylindrical consisting of large number of segments. Head bears a pair of short seven jointed antennae, a pair of mandibles and a pair of maxillae forming gnathochilarium. Each trunk segment, except the first four and last segment, bears two pairs of legs.
Poison jaws are absent. Stink glands present along the sides of the body. Genital opening on the third segment behind the head. Sexes are separate. Julus is found hidden usually in dark and damp places under stones or wood or in decaying leaves.
Arthropoda: Type # 21. Scolopendra:
Body of Scolopendra (Fig. 81.21) is elongated and dorso-ventrally flattened with numerous segments. Head is distinct and bears a pair of antennae, a pair of mandibles and two pairs of maxillae. Trunk segments numerous, each bearing a single pair of legs. First pair of trunk appendages or maxillipedes bears a sharp claw connected with the poison gland.
Genital opening is situated at the hind end of the body. Sexes are separate. Carnivorous, feeding on insects, spiders, worms, slugs, etc. Scolopendra commonly occurs under stones in rotten logs and in houses in damp places.
Arthropoda: Type # 22. Lepisma:
Lepisma (Fig. 81.22) is commonly known as silver fish. Body is flattened covered with silvery scales. Head bears a pair of many segmented antennae and a pair of ocelli. Mouth parts are biting and chewing type. Thorax bears three pairs of legs but devoid of wings. Abdomen eleven segmented with a pair of long many jointed cerci and a median caudal filament. Lepisma is commonly found in damp cool places and in books.
Arthropoda: Type # 23. Collembola:
Collembola (Fig. 81.23) is commonly known as spring tail. Body is nearly cylindrical and divisible into head, thorax and abdomen. Head bears 4-6 segmented antennae and simple eyes. Compound eyes and trachea are absent. Mouth parts are biting and chewing type. Thorax bears three pairs of legs. Wings are absent. Abdomen is six segmented.
On the ventral surface of first abdominal segment is a tube-like projection or collophore. Fourth abdominal segment bears a springing organ, the furcula, on the ventral surface. Collembola is found in crevices of bark, in moss, under stones, leaves and wood, etc.
Arthropoda: Type # 24. Locusts:
Locusts are short-horned grasshoppers, the term grasshopper is restricted to non-migratory forms, while the name locust is reserved for the migratory destructive phase.
They have antennae much shorter than the body with not more than 25 segments, they possess stimulatory apparatus of pegs on the hind femurs which is rubbed against hard tegmina to make the latter vibrate to produce a sound in males, the females are noiseless; the first segment of abdomen has a pair of auditory organs.
The female has a short ovipositor made of separate plates with which it digs holes in the earth and deposits 30 to 100 elongated eggs, a glutinous fluid is discharged on eggs which hardens to form a waterproof egg-sac, a female in one season deposits 20 such masses of eggs; the eggs hatch into nymphs which undergo 5 to 8 ecdyses to become adults.
Locusts are voracious devourers of vegetation and crops both as nymphs and adults.
Locusta migratoria is one of the chief migratory locusts of the old world, it extends from Eastern Europe to the Philippine Is. It is 5 cm long and yellowish or green in colour.
Schistocerca gregaria is one of the best known species, it is 5 cm or more in size and has yellow non-migratory phase and pinkish migratory phase with dark patches on tegmina in both phases; it extends from North Africa to North India where it causes tremendous damage to crops.
Cyrtacanthacris succinata, the Bombay locust is reddish, it is confined to India. Melanoplus and Schistocerca americana are confined to North America.
Phases and Biology:
Locusts are polymorphic, they exist in three phases:
1. A migratory phase or phase gregaria.
2. Solitary phase or phase solitaria.
3. Intermediate phase or phase transiens.
1. Phase gregaria has black and yellow or orange colour in its nymphal instars which are formed in any environment, in the adult the pro-notum is somewhat concave with a prominent constriction, the wings are proportionately longer, on reaching sexual maturity the colour changes, especially in the male.
This phase is gregarious both as nymphs and adults; when their number increases they form large, dense swarms and migrate from their breeding grounds.
Causes of migration are not fully understood, they may be due to certain favourable ecological conditions or some gregarious instinct which bring about migration. Both pairs of wings are used in migration and they reach new grounds where they eat up all vegetation.
Cessation of flight is due to physiological causes including maturation of gonads. Then they reproduce in the new grounds, and the progeny develops into phase solitaria when the environment is different from the original breeding grounds.
2. Phase solitaria has a convex pro-notum with prominent longitudinal ridge called carina, there is no constriction, they are not gregarious and no colour changes occur on sexual maturity. Their nymphs undergo colour changes simulating the colour of the environment.
3. Phase transiens shows a tendency towards one or the other two phases according to whether they are developing towards the solitary or gregarious condition, they are, thus, of various intermediate grades. Experimentally it has been shown that eggs reared in isolation produce the solitaria phase, while those reared collectively in large numbers develop into gregaria phase.
Arthropoda: Type # 25. Gryllus:
Gryllus (Fig. 81.25) is the common house-cricket. It lives in damp warm places like under logs, stones and boxes, in holes, behind books and crevices and in the kitchens.
The body is divided into head, thorax and abdomen. Head bears a pair of compound eyes and a pair of antennae which are filiform and longer than body. Mouth parts are mandibulate and well developed. Forewings are hardened and are called tegmina and hind wings are membranous.
The tibia of the forelegs bear tympanic organ and the hind legs are modified for jumping. The female possesses a well developed ovipositor that serves for depositing the eggs in crevices and holes. It produces familiar sound with its stridulating organs. It is nocturnal and omnivorous. They are very destructive and damage the household belongings—clothes, books, food etc. They also attack the growing plants.
Arthropoda: Type # 26. Mantis:
Mantis (Fig. 81.26) is commonly known as praying mantis. Body is elongated and divisible into head, thorax and abdomen. Head is small and triangular bears large compound eyes and three ocelli. Antennae are long and filiform. Mouth parts are biting type. Prothorax is much elongated and the prothoracic legs are modified for grasping and holding the prey.
Wings are folded flat and overlapping the sides of the body. Abdomen is ten segmented. Ovipositor is not erected. It is carnivorous feeding on other insects. Mantes lie in wait for their prey, the forelegs are raised in an attitude of prayer, hence, the common name praying mantis. Mantis is found living in the area of plantation.
Arthropoda: Type # 27. Carausius (Stick Insect):
Carausius (Fig. 81.27) is commonly known as stick insect. Body is elongated and slender having a stick-like appearance. Head is small and bears compound eyes and a pair of long filiform antennae. Thorax is elongated bearing three pairs of long slender legs. Wings absent. Abdomen ten segmented. They are herbivorous and eat on the leaves, etc. Carausius is found in tropical forests in the thick vegetation.
Arthropoda: Type # 28. Forficula (Earwig):
Forficula (Fig. 81.28) is commonly known as earwig. Body is elongated and covered by tough chitinous covering.
Mouth parts are biting and chewing type. Forewings or tegmina are short, leathery and truncate but the hind wings are large, membranous. Forceps-like cerci at posterior end of abdomen. They are nocturnal and feeding on vegetation. Forficula is commonly found in moist places under stones in decaying vegetable matter, etc.
Arthropoda: Type # 29. Pediculus:
Pediculus (Fig. 81.29) is commonly known as human louse. Body is dorsoventrally flattened and pale in colour with dark marking along the sides. Head small, bears a pair of compound eyes and a pair of five segmented antennae. Mouth parts are piercing and sucking type.
Wings are absent. Each leg bears a large curved claw adapted for clinging to the hairs of the host. Abdomen nine segmented. Pediculus humanus is found as an ectoparasite of man. In fact, Pediculus humanus capitis is the human head-louse that occurs clung to the head hairs, whereas Pediculus humanus corporis is the body louse that mostly harbours the hairs of arm-pit and pelvic region.
Arthropoda: Type # 30. Dragon-Fly:
Body of dragonfly (Fig. 81.30) is slender, divisible into head, thorax and abdomen. Head bears a pair of large compound eyes and a pair of short inconspicuous antennae. Mouth parts biting and chewing type. Two pairs of membranous wings present and are held in a horizontal position.
Abdomen long cylindrical with male copulatory organs on the second and third sternites. Nymphs are aquatic, breath by rectal gills and feeding upon aquatic insects and other organisms. Dragon-flies are strong fliers and strong hunters. Dragon-fly is commonly found flying in the air in the vicinity of water.
Arthropoda: Type # 31. Belostoma:
Belostoma (Fig. 81.31) is commonly known as giant water bug. Body is elongated covered by leathery exoskeleton, brownish in colour and reaches the length of 10 cm. Head is broad and bears eyes and small inconspicuous four segmented antennae. Mouth parts piercing and sucking type.
Thorax broad, somewhat triangular or narrower anteriorly. Wings leathery, well developed and hemielytra large. Legs flat, fore pair short and raptorial, middle and hind legs serve for swimming. It is carnivorous, feeds on insects, snails, fry and tadpoles. Belostoma is found in ponds and lakes in tropical countries.
Arthropoda: Type # 32. Butterflies:
Butterflies are familiar and fascinating insects generally seen in gardens. Body slender, delicate and completely clothed with hairs and scales. Head small, bears a pair of compound eyes and a pair of clavate antennae. Mouth parts sucking type with a conspicuous long coiled proboscis and are commonly called siphoning type.
Two pairs of well developed wings are present which are covered by scales. Larvae are known as caterpillars. Butterflies are diurnal or day fliers and suck the nectar from the flowers. Butterflies are commonly found in gardens flying over the flowering plants.
Arthropoda: Type # 33. Moths:
Moths (Fig. 81.33) are the close allies of butterflies. Their antennae are short and feather-like and the body is stout. At rest their wings are held horizontally. Moths are nocturnal or night fliers. They come on the light during rainy season. These are very attractive insects.
Examples of moths are cercopia moth, cloth moth, sphinx moth, etc. The common cloth moth is Tinea pellionella.
Arthropoda: Type # 34. Ants:
The best known and most numerous of insects, the ants are the dominant insects and outnumber all other land animals. This is really the age of ants. All ants are social and no truly solitary species is known. Ants show polymorphism like honey bees and termites. They are distinguished from other insects by the presence of one or two nodes between the propodaeum (thorax) and gaster (abdomen), elbowed antennae.
Typically an ant colony comprises the following types of individuals workers or ergates soldiers or degenerates, gyne or fertile female or queen and aner or fertile males. The workers are sterile, apterous females, the smallest members of the colony and often also polymorphic. The soldiers are sterile females and peculiarly modified workers with enormous head and mandibles, fitted for crushing and fighting.
The gyne or fertile females or queens are large and often enormous with wings and well-developed reproductive organs.
The aner or fertile males possess well developed reproductive organs and male genitalia. The queen, once fertilised during the nuptial swarming, dealates herself and establishes the first nest and rears her first brood. She draws her nourishment from the now-useless flight muscles and the stored-up fat.
When the first larvae appear, they are fed by a special nutritive secretion of the salivary glands and as soon as the; first workers appear, they go forth into the world, foraging. Then they can take over all the duties of the rearing of the brood, foraging, nest-building, cleaning, nursing, fighting, etc. The queen thence forward continues to lay eggs for nearly fifteen years.
The population of a single colony varies considerably from a few thousand to over 500,000 individuals.
The formicaria or the ant nest is established in a bewildering variety of situations, such as underground, inside hollow stems, fruits, thorns, galls, among leaves, etc. The tropical Oecophylla smaragdina webs leaves of various trees with silken threads into a nest. The larvae secrete the silk and are used by workers as a kind of living thread-ball.
The common Indian species of ants are as follows:
1. Monomorium—Large black ants found in crevices of walls, tree trunks, etc.
2. Camponotus—Common black house ants.
3. Solenopsis—Small red ants of house.
4. Dorylus—Wasp-like winged ants which appear around light after rains.
5. Aenictus—Common army ants that are gregarious.
Arthropoda: Type # 35. Wasps:
The wasps are very familiar insects of yellow or chestnut red body. They build nest of mud or paper pulp (wood fibre finely masticated) over walls, ceilings and trees, in holes or underground. The common Indian wasp is Vespa orientalis (Fig. 81.35) a chestnut red coloured insect.
The head bears a pair of compound eyes, three ocelli and a pair of antennae and chewing mouth parts. The thorax and abdomen are joined through a narrow and small pedicel. Thus, the abdomen is pedicellate. The female possesses a well developed sting whose infliction is quite painful.
The social wasps are trimorphic queens, workers and males. The queens are fertile females, the workers sterile females and the males are the result of development of un-fertilised eggs or of eggs laid sometimes by the sterile workers that cannot be fertilised. The nest is made in a variety of situations such as on trees, in holes or underground.
The queen starts nest building in spring and constructs a few hexagonal cells of paper pulp. The first workers then take over and enlarge the nest, until it becomes a flourishing colony.
They feed on insects, meat, fruit-juices, sugar, honeydew, sweet-meat and candies, etc. Vespa is widely distributed. Vespa vulgaris V. germanica, V. cincta and other related species are ground nesters and V. sylvestris suspends its nests from trees.
The genus Polistes which suspends its nests from trees, belonging to a closely related family Polistidae, distinguished by the slender body and short petiole. Polistes hunts on caterpillars and also feeds on fruit-juices.
Arthropoda: Type # 36. Xenopsylla:
Xenopsylla (Fig. 81.36) is commonly called rat flea. Its body is laterally compressed without wings. Integument is heavily sclerotized, brown in colour and armed with spines and bristles.
Head is closely set into thorax with front at tubercle and often with genal ctenidia. Antennae are clavate, short and concealed in grooves. Compound eyes are absent. Thorax is compact with segmentation distinct often with pronotal ctenidia on the posterior margin, prosternum is large.
Walking legs are elongated, clawed and modified for jumping. Mouth parts are piercing and sucking type. The adult flea is active and slips through hair with great ease. Xenopsylla cheopis is an ectoparasite of mammals specially rats. It transmits the plague from rats to man.