Proceedings of the South & East African combined agricultural, cotton, entomological and mycological conference held at Nairobi, August, 1926

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Monograph

Identifikator:: 1738588467

URN:: urn:nbn:de:zbw-retromon-115043

Document type:: Monograph

Title:: Proceedings of the South & East African combined agricultural, cotton, entomological and mycological conference held at Nairobi, August, 1926

Place of publication:: Nairobi

Publisher:: East African Standard

Year of publication:: 1926

Scope:: VI, 337 Seiten; Ill.

Digitisation:: 2020

Collection:: Economics Books

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Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part IV. Etomology & Mycology

Collection:: Economics Books

PART IV. Nores oN THE Lire History. Eggs are laid in the soft green tissues near the tips of stems and branches, usually in the nodes. The average incubation period is eighteen days. The nymphs move actively when disturbed; they are responsible for considerable damage during their five instars which average respectively four, three, four, five, and six days, a total of 22 days. Adults are very active and they quickly take to flight when disturbed; they feed on the same parts as the nymphs and also on somewhat older leaves. The minimum pre-oviposition period was found to be 10 days. Four eggs every day was the usual number laid throughout the egg-laying period, and the maximum number of eggs laid by a female in the laboratory was 454. The maximum longevity of the female was 126 days and that of the male 75 days. DESCRIPTION OF STAGES. The egg is translucent, creamy-white, circular in cross-section, bluntly pointed at both ends, elongated and slightly curved. The length is 1.75 m.m. and the maximum breadth 0.25 m.m. At the outer end are two delicate white filaments, 0.36 m.m. and 0.18 m.m. long, probably for respiratory purposes; around this end of the egg and covering the bases of the filaments is a brownish granular substance secreted by the bug, apparently for protection of the egg. The sole indication of the presence of eggs are the white filaments protruding from the plant tissues; careful examination is necessary to locate the eggs, the filaments being barely visible to the unaided eye. The nymph is flattened and rather broad in proportion to the length as compared with the adult. There are short hairs on all parts including antenne, legs and wing-lobes. The general colour dorsally is pale clay-yellow with paired vermillion spots on the abdomen surmounted by tufts of short brown hairs; latero-dorsally between the sixth and seventh abdominal segments is a pair of dark brown spots carrying similar hairs. The legs are creamy white with black spots on the femora and tibize but not on the tarsi. The ventral surface is pale yellow. The eyes and first antennal joint are vermillion coloured, the second antennal joint is ereamy white with a yellow band near the apex, the third is black, and the fourth reddish-brown. The nymph feeds on the underside of the leaves producing the characteristic spots. The adult is clothed by short hairs on all parts including the hemelytra. Dorsally the colour is ochrous brown with a median 0.5 m.m. broad, black line on the head and prothorax narrowing on the scutellum and joining the black membraneous part of the hemelytra. Ventrally the body is black with a median pale yellow area extending along the thorax to the fifth abdominal segment. The coxai, femora, and tibie are black while the trochanters and first three tarsal joints are pale yellow, the last two being dark brown. The eyes are Indian red. The first three segments of the antenns are black and the fourth is ochrous brown; the lengths of the joints are approximately proportional to the numbers 2—6—4—1. The sexes are slightly different in size, the female being 10 m.m. long and 8 m.m. broad at the base of the hemelytra, while the male is 9 m.m. and 2.5 m.m. excluding the antennw; the ovipositor is indicated by a ridge in the median line from the seventh abdominal segment to the tip of the abdomen. 197

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