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List of top twenty-four types of typical (Generalized) insects.
Insect: Type # 1. Lepisma (Silver Fish):
It is common household pest, usually found in cool damp places, such as among old books, under picture frames, wall papers, clothes, etc. It is wingless. Lepisma does not undergo metamorphosis. The silver fish commonly feeds on starch, and cause considerable damage to books and clothes.
Insect: Type # 2. Mayflies:
The mayflies are the shortest-lived insects and hardly survive a couple of days.
Insect: Type # 3. Cimex (Bed Bug):
It lives as ectoparasite and sucks human blood so it is sanguivorous. Sometimes, they show cannibalism. The mesothorax is usually hidden by two small wing pads, which are the vestigial fore wings. The hind wings are completely absent. It is supposed that the germs of typhoid, plague, kala-azar, tuberculosis, relapsing fever, etc. can be transferred by them.
Insect: Type # 4. Vespa (Wasp):
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They are colonial, polymorphic and social insects, living in the hives. The body is yellowish in colour. They are trimorphic. The workers have a powerful sting by which they can inject into the human body causing pain.
Insect: Type # 5. Aphis (The Aphid):
The aphid sucks plant sap. It excretes ‘honey dew’ through the cornicles (honey dew tubes). The ‘honey dew’, being sweet is eaten by ants. The ants domesticate the aphids for this purpose. Such aphids are called “ant cows”. The female aphids are viviparous and reproduce by parthenogenesis. Aphids are serious pests. They damage the plants by sucking their sap.
Insect: Type # 6. Beetles:
They are mostly pests of crops. The fore-wings are thickened, leathery, hard and opaque, which are called wing covers or elytra. They are not used for flight.
The order Coleoptera in which the beetles are placed, is the largest order in the animal kingdom. Herbivorous beetles feed on vegetables, thus they spoil useful crops. They also spoil stored food grains. Some carnivorous beetles feed on aphids, the harmful insects, therefore, they are useful in this respect.
Insect: Type # 7. Butterflies:
They are diurnal in habit. Pieris (the cabbage butterfly) lays eggs on cabbage leaves. The larvae are worm-like and called caterpillars. They are usually coloured insects. Most of the butterflies are quite destructive, as they feed on crops, orchards, gardens, etc. They are useful in cross pollination.
Insect: Type # 8. Locust:
There are many locusts but Schistocerca gregaria (desert locust) and Locusta migratria (migratory locust) have been known from time immemorial. They are the most destructive of all insects. Locusts come to India from Pakistan. Locusts are serious plant pests.
Insect: Type # 9. Poecilocerus pictus (Ak-grasshopper):
Grasshopper is essentially a solitary insect. Poecilocerus pictus lives on Ak plants. It feeds on leafy vegetation. Therefore, it sometimes causes serious damage to the crops.
Insect: Type # 10. Pediculus (Human louse):
Pediculus humanus is an ectoparasite of human beings and feeds on their blood. Eyes are poorly developed. Wings are absent. They suck the blood and carry germs of typhus fever.
Insect: Type # 11. Xenopsylla (Rat flea):
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Xenopsylla cheopis is an ectoparasite of rats and men and feeds on their blood. Wings are absent. Xenopsylla cheopis transmits Bacillus pestis from rat to man which causes bubonic plague.
Insect: Type # 12. Musca (House Fly):
They are saprophagous in diet, viz., taking fluid only. Mandibles are absent. They are very harmful insects because they spread the germs of some dangerous diseases, such as cholera, typhoid, paratyphoid, anthrax, diarrhoea, dysentery, tuberculosis, etc.
Insect: Type # 13. Mosquitoes (Fig. 4.28):
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The males generally feed on plants juices, while the females feed on blood. Its saliva contains anticoagulant. There are present piercing and sucking type of mouth parts. Mandibles are absent in male mosquito. The metathorax bears two club-shaped processes known as halteres or balancers.
The pedicel (second segment) of the antenna contains Johnston’s organ which perceives sound vibrations like an auditory Organ (hearing organ). Plasmodium (Malarial Parasite) which causes malaria fever is transmitted by the female anopheles.
Filaria which causes filariasis is transmitted by Culex. Encephalitis is caused by a virus in man, which results in high fever, headache, drowsiness and inflammation of the brain. This virus is also transmitted by some species of Culex. Aedes mosquito transmits virus of Dengu fever, Yellow fever and Chikungunya.
Insect: Type # 14. Termites (White ants):
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Termites are colonial, polymorphic and social insects. In the colony, mostly two forms are present; fertile caste and sterile caste. Fertile castes include the fertile males and females.
Sterile castes include both males and females but are without wings and their reproductive organs are vestigial. Sterile castes include workers, nasutes and soldiers. During the breeding season, the winged male and female fly together which is known as nuptial flight during which copulation occurs,
(i) Queen:
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She lays eggs.
(ii) King:
The king fertilizes the queen.
(iii) Workers:
The workers construct and repair the nest (termitarium), collect the food, look after the eggs and feed the nymph and other castes.
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(iv) Nasutes:
They have at the tip of head opening of the frontal gland. The secretion of this gland is sticky in nature and used in the warfare during which it is inflected upon their enemies. This secretion is also used to dissolve hard substances, which workers face during nest formation.
(v) Soldiers:
They defend the colony. The main food constituent is cellulose, which they obtained from wood or wood work. They are able to digest cellulose with the help of certain flagellates such as Trichonympha that live in their intestine. The exchange of food between one insect and the other is called tropholaxis which is common in termites.
Insect: Type # 15. Ants:
Like termites they are social, colonial and polymorphic insects. Tropholaxis is common in the ants. Generally male and female go on a nuptial flight. After mating, the males usually die. The mated females shed their wings and lay eggs in the nests.
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The main castes of ants are the following:
(i) Queens:
They are fertile females. They may live up to 15 years in some species,
(ii) Kings:
They are fertile male ants,
(iii) Workers:
Actually they are sterile, wingless females, which are smallest in the nest. The workers take over the feeding of the queen and larvae. They also store the food and build the nests,
(iv) Soldiers:
They are modified workers bearing large head and powerful serrated mandibles. They protect nest from the enemies. Ants destroy in bulk seeds and grains from fields and godowns. Their useful activities are helpful in pollination, act as scavengers by disposing dead bodies of animals, increase the fertility of soil by burrowing.
Insect: Type # 16. Silk Moth (Bombyx mori):
It is also called mulberry silk moth, which never occurs in the wild state and is a completely domesticated moth. It is called “Resham- Ka- Kira” in Hindi. It is extensively cultivated all over the world. In India, Kashmir, Mysore and Coimbatore are the main silk producing centres. The adults do not feed and survive for two to three days only. They fly very rarely.
The male dies soon after copulation and female after laying eggs. The silk is obtained by killing the pupa inside the hot water. Then, the silk thread is wound. About 1000 metres of silk thread can be obtained from a single cocoon and about one pound of silk can be obtained from 25000 cocoons. Rearing of silk moth for obtaining raw silk is called sericulture. It is done on large scale in China, Japan, Italy, France, Brazil, India, etc.
Insect: Type # 17. Apis (Honey Bee):
Species of Honey bee are:
(1) Apis mellifera — Italian bee,
(2) Apis dorsata— Rock bee – largest,
(3) Apis indica— Indian bee,
(4) Apis florea— Little bee – smallest.
Most common Indian honey bee in wild state is Apis indica, however in domestic state; the most common Indian honey bee is Apis mellifera (Italian honey bee). Honey bees are colonial, social and polymorphic insects. Unfertilized eggs develop into drones (males) by parthenogenesis. Fertilized eggs develop into queens or workers.
Three types of individuals (castes) are found in the colony of honey bees:
(i) Queen is a fertile female,
(ii) Drones are males. Life span of a drone is 1-2 months,
(iii) Workers are sterile females and perform various duties of the colony. The queens are fed by the workers. The abdomen contains the wax glands and the sting.
The worker bees of a hive fall into three major castes:
(a) Scavenger or Sanitary bees. For the first three days each worker bee acts a scavenger.
(b) House or Nurse bees. From the fourth day onwards, each worker bee feeds like a foster mother, with a mixture of honey and pollen.
From the seventh day, the maxillary glands of a worker bee secrete “royal jelly” to feed young larvae, the queen and those older larvae which are destinated to develop into future queens. From the twelfth to the eighteenth day, each worker bee develops wax glands. Wax is secreted in the form of thin scales,
(c) Foraging or Field Bees. When a worker bee is about 15 days old, it explores new sources of nectar and pollen and collects these and water. These bees are also called scout bees. Ernest Spytzner (1788) was the first to draw attention to the fact that bees communicate by means of definite movements now called “bee dances”.
Prof Karl von Frisch decoded the language of “bee dances” and got Nobel Prize in medicine or physiology for it in 1973. He discovered that scout bees perform two types of dances for communication.
(i) Round dance is performed when a newly discovered food source is close (less than 75 metres) to the hive
(ii) Tail wagging dance is performed for long distance sources. Lifespan of a worker honey bee is 3-4 months.
Economic importance:
(i) Honey bees provide honey. Honey is a natural valuable tonic for human body. It contains enzymes, vitamins, monosaccharide sugars mainly glucose and fructose, pigments, ash, moisture, minerals and so on. Honey has neutral ph. Honey also acts as antiseptic,
(ii) Bee wax is used in making candles, polishes, toilet goods, cosmetics, electric goods, carbon paper, etc.
(iii) Honey bees help in the pollination of flowers of fruit plants and seed crops,
(iv) Their sting is poisonous and sometimes fatal to man when they attack in large numbers.
Rearing of honey bees to obtain honey and bee wax is called apiculture. A place where bees are kept is known as apiary. A person who keeps bees is called apiarist.
Insect: Type # 18. Laccifer (Tachardia) lacca— Lac Insect:
It is found in thick forest in India, Myanmar (Burma), Ceylon (Sri Lanka), Thailand, Philippine Island, Formosa and East Indies. The females are degenerate individuals, without wings, legs and eyes. The body of the female is soft, ovoid and without segmentation. It has at the anterior end a 2-jointed rostrum and 2- short processes bearing a pair of spiracles.
Male has a segmented body divisible into head, thorax and abdomen. The abdomen bears at its end a pair of long anal hair. There is sexual reproduction. The females can also reproduce parthenogenetically. The males are active and females are motionless.
During unfavorable season, the females secrete lac to form protective nest for egg laying upon branches of Peepal, Dhak, Bargad and other trees. Nymphs, not larvae, hatch- out from the eggs. Lac is scraped from the surface of trees, crushed and sieved to produce lac dust.
It is used in the manufacture of shellac, varnish, polish, buttons, bangles, toys and some electrical items. A dye is prepared from dead and dried bodies of the females. This dye is used by women folk of our country for mahavar. India is the major lac producing country.
Insect: Type # 19. Sympetrum (Dragon Fly):
The dragon flies are mostly found in the vicinity of water. They are also called the “mosquito hawks” as their main diet is mosquitoes. Thus, they help in controlling malaria. The female lays eggs in the water.
The naiads are stout, and their rectum is elongated to form a rectal respiratory chamber in which the gaseous exchange takes place. In the rectal chamber, the naiad draws water and then expels out. This is an unusual structure, which occurs in naiads of dragon fly only.
Insect: Type # 20. Mantis (Praying mantis):
Praying mantis is usually found on the leafy vegetables, where it feeds on other insects which it captures by means of their prehensile fore-legs. Cannibalism is very common in these insects. Praying mantis destroys certain harmful insects, so it is a useful insect.
Insect: Type # 21. Palamneus (Scorpion):
It is viviparous. The body is divisible into (i) anterior the prosoma and (ii) posterior the opisthosoma.
(i) Prosoma:
It is un-segmented and covered by a carapace. The latter bears a pair of large median eyes and two groups of smaller lateral simple eyes, each group comprise three eyes. Ventrally the prosoma has a sternal plate and six pairs of appendages, i.e., one pair of small chalicerae, one pair pedipalpi and four pairs of walking legs.
(ii) Opisthosoma:
It is differentiated into anterior mesosoma and posterior metasoma.
(a) Mesosoma:
It is made of seven segments. The sternum of the second segment bears a pair of comb-like sensory appendages, the pectines. The sternum of each of 3rd, 4th, 5th and 6th mesosomal segments bears a pair of oblique slit like openings the stigmata, which lead into respiratory organs, the book lungs,
(b) Metasoma:
Its posterior narrow part consists of five segments. The last segment bears the anus and a stinging apparatus or telson. The latter consists of a swollen base, the vesicle or ampulla and a curved and pointed spine, the aculeus. Inside the vesicle lies a pair of poison glands, the ducts of which open by a pair of minute apertures at the tip of the spine.
Insect: Type # 22. Aranea (Spider):
The body is divisible into an anterior cephalothorax and a posterior abdomen. The cephalothorax has six pairs of appendages (one pair of chelicerae, one pair of pedipalpi and four pairs of walking legs).
The abdomen is un-segmented, rounded and without telson but has three pairs of spinnerets or spinning organs which produce threads for the construction of spider web. Book lungs and the tracheae are the respiratory organs. Excretory product of spider is guanine. Poisonous spider is Lectodectus meactans.
Insect: Type # 23. Sarcoptes (Mite):
Sarcoptes scabiei is a dangerous ectoparasite which attacks man, causing scabies, producing severe irritation. Anterior two pairs of legs are stronger. Posterior two pairs of legs are shorter and attached more ventrally and carry long bristles.
Insect: Type # 24. Ixodes. (Sheep Tick):
The body is covered with leathery skin and is without segmentation. Four pairs of legs are segmented. The tarsus of first pair of legs has a sensory cup shaped Haller’s organ. Respiration is by spiracles and tracheae. It has blood sucking mouth parts. Its saliva contains an anticoagulant which prevents coagulation of blood. It feeds on the blood of sheep.
