BLOODSUCKING INSECTS AND TROPICAL DISEASES. 163 



Ceratopogonince, which is represented throughout the world, and at the pre- 

 sent time comprises nearly four hundred described species. The blood-suck- 

 iug habit, however, i3 by no means universal even among Ceratopogonince, and 

 is limited to the female sex. 



Appearance. — Extremely small flies, as a rule (in the case of species known to 

 suck blood), not exceeding 1^ or 2 mm. in length, though the males are usually 

 somewhat larger than the females ; generally blackish or dark grayish-brown 

 in colour, but the abdomen of the female, after feeding, often rosy, owing to 

 the contained blood. The wings when at rest are carried flat, closed one over 

 the other like the blades of a pair of scissors ; in many species they are 

 hairy, and they are often speckled or mottled with grayish-brown blotches. 

 The sexes can be distinguished owing to the possession by the males of tufted 

 antennae and a more elongate shape. 



Life-history. — As a general rule, the larva? of naked-winged species of Cera- 

 topogonince are aquatic, those of hairy-winged species terrestrial. The eggs of 

 aquatic species are laid in floating algae in star-shaped clusters containing from 

 one hundred to one hundred and fifty. The larva? of these species are whitish 

 worm-like creatures, with long narrow heads, and live in the masses of Con- 

 fervas floating on the surface of stagnant pools and ditches. They are without 

 prolegs on the prothoracic segment, and progress with a serpentine motion. 

 The pupa, which is shorter than the larva, with a conspicuous pair of respira- 

 tory horns on the thorax, is brownish in colour, possesses little power of 

 movement, and remains at the surface of the water. The larvae of the hairy- 

 winged species live under the damp bark of dead trees, in weeping spots on 

 tree-trunks, and in decaying vegetable matter generally, such as manure, rot- 

 ting fungi, etc. These terrestrial larvae are usually shorter than the aquatic 

 ones, and do not move in serpentine fashion, but are provided with a cleft 

 proleg on the underside of the prothoracic segment while the head and body 

 segments also bear peculiar lancet-shaped hairs and spines. Serpentiform 

 larvae, which have produced midges with hairy wings, have, however, been 

 found in the sap saturating diseased bark on tree-trunks. 



Habit* of the perfect insects. — In spite of their small size, the females of 

 certain species of Ceratopogonince are among the most irritating and blood- 

 thirsty of insects, both in the tropics and also in 

 temperate regions. Writing of a species found 

 in Uganda (see fig. 1), a recent observer * says : 

 " It is very common in many places, usually near 

 habitations. This minute fly can pass through 

 the finest mosquito netting ; muslin I have not 

 tried. It bites terrribly, leaving an irritating 

 wheal, which itches for days. It makes a sharp, Fj( . x ._ Cerator)0g0n sp _ ? 



short, peevish buzz when settling, fully as loud Uganda, (x 12) 



* Dr tuthbert Christ}', " lieports of the Sleeping Sickness CommiBsiou," No. III., pp . 

 39—40 (London ; Harrison & Sons, November,. 1903) 



