BLOOD-SUCKING INSECTS AND TROPICAL DISEASES. 171 



Fig. 



'J.—Lyi erosia sp, 

 Sokotra ( X 3). 



guished by the eyes being closer together in the males. Lastly, it is to be 

 noted that in all forms there is a hard ehitinous proboscis, ensheathed in the 

 palpi in the case of Tsetse-flies, which in its normal position, when not in use, 

 projects horizontally beneath and in front of the head. 



Life-history. — With the exception of Glossina the species of this group breed, 

 as a rule, in dung, depositing eggs from which are developed white maggots of 

 the type of those of the Common European Blow-fly. According to Riley and 

 Howard Lyperosia irritatis, L. ( llccmatobia serrata, Rob.-Desv.) oviposits on 



fresh cowdung, and its eggs are irregularly oval in shape, 

 flattened on one side, and from l - 25 to "137 mm. in 

 length, 0-34 to 0*41 mm. in width. The i ewly hatched 

 larvae descend into the dung, and eventually when full- 

 grown attain a length of 7 mm. Pupation takes place in 

 the ground beneath, at a depth of from half to three- 

 quarters of au inch. The puparium is of the normal 

 Muscid type, dark brown in colour, barrel-shaped, and 

 from 4 to 4'5 mm. in length, by 2 to 2*5 mm. in width. Stomoxys culcitrans, 

 L., a species that is abundant throughout Euiope and North America, usually 

 breeds in horse-droppings, and its larvae are very similar to those of the Com- 

 mon House-fly, which also breeds in horse-dung. The life history of Tsetse-flies 

 is of an abnormal type, the female producing a single larva at a time, which is 

 retained and nourished within the oviduct of the mother until full-grown, and 

 on being extruded at once crawls away and buries itself in the earth, where it 

 turns into a pupa so soon as it finds a suitable hiding place. The pupa is dark 

 brown, with a pair of prominent granular protuberance at the posterior extremity. 

 Habits of the perfect insects. — Some of the species of this group, especially 

 those of Stomoxys and Glossina, attack man as well as domestic animals, and 

 it is possible that in the case of Glossina palpalis, in certain parts of Africa, at 

 any rate, such as Uganda, human blood forms the chief food ; other species of 

 Tsetse-flies appear to subsist normally on the blood of big game.* The species 

 of Lyperosia attack horses, cattle, and camels. Jn the 

 United States Lyperosia irritans ( Hamatobia serrata ) is 

 known as the " Horn-fly " from its habit of clustering in 

 masses about the base and on the concave side of the horns 

 of cattle. According to Riley and Howard, it reduces the 

 condition of stock to a considerable extent, but statements 

 as to the death of animals from its attacks are unsubstan- 

 tiated. When feeding, the flv is fouud on the back, flanks, 

 Fig. 10.— Olussina " 



longiptnnis, tortl, legs, and under the thighs. In Europe and North America 

 from .-omaillaud, iu , . . 



vesting altitude, Stomoxys calcitrans is often found in houses, 

 showing > he nositio:i , _ _,, .. , . „ „. 



of the wings (x i$). A Blood- sucking Larva. — The so-called " Congo .Floor- 



* For further information on the habits, etc., of Tsetse-flies, see •' A Monograph of the 

 Tsetse-flies," by E. E. Austen (London, 1903: published by the Trustees of the British 

 M up.eum) . 



