KEPORT ON ECONOMIC ENTOMOLOGY 
207 
Descriptions of the adults, male and female (fig. 2), were given in the Second Report 
of these Laboratories.' 
The larva (fig. 4) is ashy grey to greenish in colour, with a pale yellowish brown head. 
The posterior segments are swollen and the first thoracic segment bears a ])roleg. Both the 
proleg and the anal segment terminate in clusters of hooks. Immediately above the anal 
cluster is a transverse comb of papilli. Two eyes are situated on cither side of the head 
and the mouth is provided with a pair of delicately fringed appendages used in sweeping 
the food into the gullet. 
Length about 5 mm. 
The pupa (fig. 6) is pale chestnut hrown in colour and is enclosed in a semi-transparent, 
brown, pocket-shaped cocoon, about 3 mm. in length. Projecting above the edge of the 
cocoon is a pair of white to greyish white respiratory appendages. Each appendage 
consists of three leaf-like processes, two of which are united at the base. 
Lifii-histori/ and hahitn .— The larval stage of the Nimifti is passed in the swiftest 
running water, the eggs probably being deposited in masses on rocks and plants at the 
water’s edge. 
The larvffi, though aquatic, are poor swimmers, so attach themselves to some fixed 
support and rely on the current to bring their food to them. They are usually particularly 
numerous on debris — e.y. sticks and weeds — ^caught up among rocks. On their support 
they spin a network of silken threads by means of which they are enabled to maintain 
their position against the strongest current. Frequently they will leave their support and 
let themselves out into the stream anchored by threads of silk and enabled by them to 
return. 
When full-fed, they pupate in small pocket-shaped cocoons attached to the support on 
which the larval stage has been passed. 
The adult emerges in a bubble of air and, having gained the surface, at once takes 
wing. 
Swarms usually consist almost entirely of females. The males are not blood-suckei’s 
and are rarely seen in any numbers far from their breeding haunts. Sometimes, however, 
the first swarms of the season are made up largely of males — this was the case in 1906. 
The powers possessed by even the females of actually blood-sucking are very limited, 
so far as human beings are concerned, as they appear to be unable to pierce the skin except 
in places such as immediately behind the ear, the forehead, etc. I have never seen them 
gorged with blood even from these situations. They nevertheless cause intense annoyance 
both by their habit of crawling into the eyes, ears and nose, and also by continually 
pricking the skin in their ineffectual efforts to obtain blood. 
They feed mainly on birds and animals. 
On alighting upon a suitable host — e.ij. a donkey—the fly creeps down through the 
hair until it reaches the skin, whereupon it inserts its proboscis and commences to suck 
blood. In a short time its abdomen becomes enormously distended and the insect then 
makes its way back out of the hair and attempts to fly. Usually, owing to the quantity of 
blood it has imbibed, it is unable to proceed more than a few yards before falling to the 
ground. It then hides itself among the vegetation until the immediate effects of its feast 
have passed away. 
When walking over a smooth surface, the Nimifti wave their forelegs, ajiparently using 
them as feelers. This habit is common to many of the larger Tahanidie. 
Nifuitti flies 
Larva 
Pupa 
Life-history 
and habits 
Second Report, Wellcome Research Laboratories, 19U6, pp. 52, 53. 
