Orthoptera Acrididae, Gryllidae; Dictyoptera Mantidae, Blattidae; Odonata; Isoptera Termitidae. Thysanoptera Thripidae.
Order - Orthoptera
Synonyms: Saltatoria, Saltatoptera
Etymology: Ortno - straight; ptera-wings.
Common names: Grasshoppers, Locust, Katydid, Cricket, Mole cricket
Characters
They are medium to large sized insects.
Antenna is filiform.
Mouthparts are mandibulate.
Prothorax is large. Pronotum is curved, ventrally covering the pleural region.
Hindlegs are saltatorial
Forewings are leathery, thickened and known as tegmina.
They are capable of bending without breaking.
Hindwings are membranous with large anal area. They are folded by longitudinal pleats between veins and kept beneath the tegmina.
Cerci are short and unsegmented.
Ovipositor is well developed in female.
Metamorphosis is gradual. In many Orthopterans the newly hatched frist instar nymphs are covered by loose cuticle and are called pronymphs. Wing pads of nymphs undergo reversal during development.
Specialized stridulatory (sound-producing) and auditory (hearing) organs are present.
Classification
This order is sub divided into two suborders, viz., Caelifera and Ensifera.
Acrididae: (Locusts, Grasshoppers)
Antenna is short
Tarsus is three segmented
Ovipositor is short and horny
Tympanum is located one on either side of the first abdominal segment.
Sound is produced by femoro-alary mechanism. A row of peg like projections found on the innerside of each hindfemur is rubbed against the hard radial vein of the closed tegmen.
Locusts are a serious threat to tropical agriculture. They swarm under favourable conditions and mainly feed on grasses, cereals etc.
Gryllidae (Cricket)
Antenna is long.
Tarsus is four segmented.
Ovipositor is slender and needle like.
Forewings are abruptly bent down to cover the sides of the body
Hindwings are acuminate. They are produced into a pair of long processes which project beyond the abdomen.
Cerci are long and unsegmented
Auditory organs and stridulatory organs are similar to long horned grasshopper. Males stridulate during night. They produce a shrill chirping noise.
Gryllus sp. It is household pest.
Order - Dictyoptera : Mantidae, Blattidae
Synonyms : Oothecaria, Blattiformia
Common names : Cockroaches and preying mantids.
Characters
Head is hypognathous.
Antenna is filiform.
Mouthparts are chewing type.
Tarsus is five segmented.
Forewings are more on less thickened, leathery with a marginal costal vein. They are called tegmina.
Hindwings are large, membranous and folded fanlike and kept beneath the forewings.
Cerci are short and many segmented.
Eggs are contained in an ootheca.
Classification
Dictyoptera is divided into two suborders viz., Blattaria (cockroaches) and Mantodea (preying mantids).
There are two important families viz., Blattidae and Mantidae
Order - Odonata
Etymology: Odon - tooth
Common names: Dragonflies and damselflies
Characters
Medium to large sized insects
They are attractively coloured
Head is globular and constricted behind into a petiolate neck.
Compound eyes are large.
Three ocelli are present
Mouthparts are adapted for biting. Mandibles are strongly toothed Lacinia and galea are fused to form mala which is also toothed.
Wings are either equal or sub equal, membraneous; venation is net work like with many cross veins. Wings have a dark pterostigma towards the costal apex. Sub costa ends in nodus. Wing flexing mechanism is absent.
Legs are anteroventrally placed. They are suited for grasping, holding and conveying the prey to the mouth. Spinose femora and tibiae are useful for holding the prey. Forward shift of leg attachments allow easy transfer of prey items to mouth in flight. Legs are held in such a way that a basket is formed into which the food is scooped.
Abdomen is long and slender. In male gonopore is present on ninth abdominal segment.
But the functional copulatory organ is present on the second abdominal sternite. Before mating sperms are transferred to the functional penis. Cercus is one segmented.
Metamorphosis is incomplete with three life stages. The naiad is aquatic. Labium is greatly elongated, jointed and bears two hooks at apex. It is called mask. It is useful to capture the prey.
Importance
Adults are aerial predators. They are able to catchhold and devour the prey in flight. Naiads are aquatic predators. Dragonflies and damselflies can be collected with an aerial net near streams and ponds especially on a sunny day. Naiads can be collected from shallow fresh water ponds and rice fields.
Classification
There are two sub-orders. Dragonflies are classified under Anisoptera and damselflies are grouped under Zygoptera.
Order - Isoptera -Termitidae
ETYMOLOGY: 'iso' meaning equal and 'ptera' meaning wings
COMMON NAME: Termites
Characters
Pale, elongate bodies, and are sometimes called “white ants.”
Reproductive individuals have two pairs of membranous wings, all of equal length.
Termites shed their wings after mating.
Have chewing mouthparts.
Antennae are roughly the length of their heads.
Classification
Hemimetabola - incomplete development (egg, nymph, adult) Orthopteroid - closely related to Blattodea and Mantodea
Major Families
Rhinotermitidae (Subterranean termites) -- These insects build nests in the soil and generally infest wood that is in contact with the ground.
Hodotermitidae (Rottenwood termites) -- Generally found inhabiting moist wood. Contact with the soil is not a requirement.
Kalotermitidae (Drywood and dampwood termites) -- These insects nest in the wood itself and do not require contact with the soil.
Termitidae -- This is the largest family of termites worldwide.
Termitidae Physical Features
ORDER - THYSANOPTERA-THRIPIDAE
Synonyms : Physopoda
Etymology : Thysano - fringe; ptera - wings
Characters
They are minute, slender, soft bodied insects.
Mouthparts are rasping and sucking. Mouth cone is formed by the labrum and labium together with basal segments of maxillae. There are three stylets derived from two maxillae and left mandibles. Right mandible is absent. Hence mouthparts are asymmetrical.
Wings are either absent or long, narrow and fringed with hairs which increase the surface area. They are weak fliers and passive flight in wind is common.
Tarsus is with one or two segments. At the apex of each tarsus a protrusible vesicle is present.
Abdomen is often pointed. An appendicular ovipositor may be present or absent.
Nymphal stage is followed by prepupal and pupal stages which are analogous to the pupae of endopterygote insects.
Classification: This order is subdivided into two suborders.
TEREBRANTIA: Female with an appendicular ovipositor. Wing venation is present.
TUBULIFERA: Ovipositor is absent. The abdomen is tubular. Wing venation is absent.
Importance
They suck the plant sap. Some are vectors of plant diseases. Few are predators.
Rice thrips: Stenchaetothrips biformis is a pest in rice nursery.