SIMULIUM : EARLY STAGES 173 



Sim-uliiim damnosum, Theobald. Body of a uniform black colour, 

 antennae and palpi black. Thorax dark with golden hairs ; abdomen 

 black with short dark hairs. The metatarsi and first two tarsi of the 

 fore legs are swollen. Larva large and of a dark colour, with a pig- 

 mented patch at the sides of the first thoracic segment. Pupa with 

 a bifid comb of tubes which do not project much above the cocoon. 

 S. damnosum is the well-known ' Jinga Fly ' of Uganda, and is widely 

 distributed throughout Equatorial Africa. 



At certain seasons Simuliidae appear in swarms and attack 

 animals and even man. They are generally met with in the vicinity 



of streams, especially where there are woods. They 



n , . , . , . , j ..." Bionomics of Simu- 



usually bite larger animals on the abdomen, either ^ 



near the scrotum or udders, or on the fore legs. 

 Other favourite places are the inside and along the margin of the ears, 

 and round the eyes. They are most active during the early part of 

 the day, from sunrise till about 10 a.m., when they retire to rest on 

 the under surfaces of leaves close to the ground. They begin biting 

 again towards evening, and may continue to do so till late at night, 

 especially during moonlight nights. When attacking man they often 

 settle on the forehead, back of the neck and the ears, and cause 

 considerable annoyance by trying to crawl into the eyes and nose ; 

 they may also bite the ankles, even through stockings. The bite is 

 sharp and stinging and causes considerable irritation. 



In 1795 Schonbauer described the early stages of the ' Columbacz 

 gnat ', Simulium columbaczence, Schon., and drew attention to the 



remarkable fact that its eggs are laid on leaves, blades 



r j j ^ 4.u i u Ear| y Stages. Plate 



of grass, etc., under water, and that the larvae attach XXX|( 



themselves to any fixed object floating in the water ; 

 when about to pupate they spin a cocoon on the support. The eggs 

 (figs. 2 and 5) are small ovoid objects, somewhat yellowish in colour, 

 usually more pointed at one end than at the other; they are often 

 distorted, and then project at one side. They are enveloped in a 

 gelatinous substance, and are spread out in an uneven layer either 

 on blades of grass or dead leaves, or on stones, etc., below the surface 

 of the water, usually where it is running swiftly ; they never lay their 

 eggs in stagnant pools. Some species oviposit only on stones, others 

 on any support under the water, especially in places where it rushes 

 rapidly round a bend. When about to lay her eggs the female crawls 

 down to the edge- of the water, inserts a part of her abdomen beneath 

 the surface, and deposits the eggs with their accompanying gelatinous 



