INSECT ORDERS OF ECONOMIC IMPORTANCE

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INSECT ORDERS OF ECONOMIC IMPORTANCE

Body relatively flat, tapered and often covered with scales
Compound eyes small or absent
Antennae long, thread-like, and multi segmented
Abdomen with ten complete segments
Eleventh abdominal segment elongated to form a median caudal filament
Cerci present, nearly as long as median caudal filament
Styliform appendages located on abdominal segments 7-9
Domestic species such as silverfish and firebrats may cause extensive damage to household goods.

Antennae filliform
Mouthparts mandibulate, hypognathous
Pronotum shield like, covering much of thorax
Front wings narrow, leathery (tegmina); hind wings fan-like
Hind legs usually adapted for jumping (hind femur enlarged)
Tarsi 3- or 4-segmented
Cerci short, unsegmented
Immature are structurally similar to adults, developing wing pads often visible on thorax.
Orthoptera is generally regarded as a dominant group in most terrestrial habitats.
These insects feed on all types of plants and often cause serious economic damage.
Swarms of grasshoppers (locusts) regularly appear in parts of Africa, Asia, and North
America and destroy crops over wide land areas.
Mole crickets are major pests in lawns and golf courses in the southern United States.
Several species of field crickets are reared commercially as fish bait.

The size of the insect varies from <1mm to >100mm.
Insect have got piercing and sucking type of mouth parts.
They may be winged or wingless. They usually have 4 wings.
They may be soft or hard bodied insects.
They are brightly or lightly coloured.
Many species have glans for secreting odours waxes, scales like coverings.
There is hemimetabolous type of development.
Basal portion of the front wings of true bus are generally thicken and coloured but membranous overlapping tips are coloured or transparent .
Hind wing are entirely membranous and hidden under the front wings.
Scutellum is usually exposed and triangular in shape.
The beak is 3-4 segmented or rostrum is 3-4 segmented.
The beak arises from the front of the head and cutves backward to extend along the ventral side of the body.
Insect feed on plant sap, seed fungi, fruit juices or blood of insect and other animals including human beings.
Many species are plant pest and few species transmit animal diseases but many are of no direct economic importance to human beings
Some are predators on some insects
Scents glands are present on the side of the thorax and they emit some peculiar odours for self-protection.
Most of the species are terrestrial but some common groups are aquatic or semiaquatic.

These are minute to small insects and are distributed widely
Head is deflexed and not generally constricted behind to form a neck.
Compound eyes well developed, ocelli absent in apterous form but 2 to 3 in winged forms
Antennae well developed and usually 3 to 10 segmented
Mouth parts piercing and sucking type, stylets often exceedingly long, retractile, rostrum arising from the back of the head, in some cases appearing to arise between anterior coxae. In some adults like male coccids the mouth parts are vestigial or absent
Thoracic segments generally fused together and not distinguishable from abdomen in wingless forms. Pronotum small and collar like.
Winged or wingless when winged the four wings are uniform in consistency and the wings are held roof like over the body at rest. Alary polymorphism is prevalent. In male coccids only one pair i.e. forewings are present.
Wax glands or honey tubes usually well developed in most of the members of this order.
In most of the species, the life history is very complex involving sexual and parthenogenetic generations winged and wingless individuals.
Usually undergo simple metamorphosis. In some species, the last nymphal instar is quiescent and pupa like.

Hard Exoskeleton and hardened pair of wings called elytra which covers the abdomen and the flight wings.
Beetles comprise the largest order of insects with over 300,000 species forming about 40 percent of the known insects.
Beetles have thickened front wings (elytra) that are soft, leathery, or hard and brittle.
The elytra usually meet in the straight line along the middle of the longer, folded, membranous hind wings. Some beetles have short elytra and or hind wings or are wingless.
Most beetles use only the hind wings for the flight; the elytra are raised to allow for hind wing movement.
The pronotum is generally distinct whereas the mesonotum and the metanotum are hidden beneath the elytra.
The mouth parts of the adults and most larvas are adopted for chewing.
Some predatory larvae are able to suck body fluid of prey.
Beetles are primarily plant feeders and scavengers, although a significant number are predators of insects and other small invertebrates and a few are parasites.
Eggs are usually deposited in an area suitable for larval development the larva sometimes called grubs, typically molt three to five times.
The immobile pupa is soft, pale and resembles the adult.

Flies are characterized by a single pair of membranous wings attached to an enlarged mesothorax.
The hind wings on the metathorax are reduced to a pair of knoblike appendages.
The halter, which help to balance the insects.
Flies range in size less than 1mm in length (midge) to 75 mm (tropical robber flies).
The compound eyes are often large; in mangy groups the expanded eyes of males meet on top of the head whereas they do not in females.
Most adult flies have sucking mouth parts that are modified for piercing, lapping or sponging the mouth parts are nonfunctional in some species.
Food consists chiefly of nectar but numerous feed on fruit juice, plant saps.
Fly larvae are usually legless and have either a distinct or greatly reduced head. The latter types are maggots.

Bees, Wasps, Ants, Sawflies, Horntails etc.
Sizes range from 0.20 mm to 65 mm in length.
Mouth parts are chewing or reduced in larvae but chewing or chewing-lapping in adults.
Antennal are fillform and geniculate etc.
Compound eyes are large but absent in ants.
Legs are long with five segmented tarsi.
Two pairs of long narrow membranous wings with fused venation are absent.
Hamuli or hooks represent on hind-wings of all winged forms.
The ovipositor may be modified into a sting.
Some species are highly social and have caste differences.
Larvae are either caterpillar-like or they are called “grubs”. Larvae herbivorous or parasitic to scavenger.
Metamorphosis is complete.
Most species have constriction between thorax and abdomen. Wingless workers of ants and sawflies are exceptions.

Adult Lepidopterans are small to large insects.
Having 200-300 mm normally wing span (Spread).
They have minute and powder like scales that covers the wings and body of most species.
Lepidopterans have usually 4 large wings. Although, some female moth are short- winged or wingless. Examples: Bagworm.
Compound eyes are large.
Antennae are long.
Moths: Filamentous or thread like antennae
Butterflies: Clavate shaped.
Skippers: having hooks like at the end.
Mouthparts are generally reduced but maxilla and labial palp are extended. The proboscis is extended to suck up the liquid food and coiled when not in use. Some moth have not proboscis.
Certain moths have membranous auditory-organs on mesothorax or abdomen.
Vision is good. Many individuals respond to motion, flower shapes, wing pattern, blue-violet and ultraviolet light.