प्रारम्भिक कीट विज्ञान/१७
ORDER - ORTHOPTERA FAMILY – ACRIDIDAE 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. Caelifera Ensifera 1. Antenna is short with less than 30 segments. Antenna is long with more than 30 segments. 2. Tympanum is found on the lateral side of the first abdominal segment. Tympanum is fund on the the foretibia. 3. Vision and hearing acute Tactile respones is well developed. 4. Mandibles are specialized for consuming monocot foliage. Feed on dicot plants 5. Diurnal Nocturnal 6. Rely on jumping to escape from predators Rely on crypsis 7. Eggs are laid in groups in soil inside shallow burrows. Eggs are singly inserted into plant tissue or soil. I. Sub order: Caelifera 1. 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. II. Sub order : Ensifera 1.Tettigonidae : (Katydids, Long horned grasshoppers) Antenna is long, slender as long as or longer than the body. Tarsus is four segmented. Ovipositor is sword like. Auditory organs are found in foretibiae. In each foretibia a pair of tympanum is present. The outer tympanum is larger than the inner. Sound production is alary type. A thick region on the hind margin of the forewing (scraper) is rubbed against a row of teeth on the stridulatory vein (file) present on the ventral side of another forewing which throws the resonant area on the wing (mirrors) into vibrations to produce sound.
2. 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.
3. Gryllotalpidae : (Mole crickets) They are brown coloured insects found inside the burrows. Eyes are reduced. Pronotum is elongate, ovate and rounded posteriorly. Forelegs are fossorial. Tibiae are expanded and digitate. Hindwings are extended beyond the tegima as a pair of processes Special stridilatory structures are absent. A humming sound is produced by rubbing the forewings. A pair of tympanum is found on the order surface of the tibiae. Ovipositor is vestigeal. Mole crickets burrow into the soil and feed on tender roots of growing plants. Gryllotalpa africana is a pest on stored potatoes. MOLE CRICKET