6S INSECTS. 



animals. Thus it is by no means uncommon for sheep to be attacked in this 

 way by a green-bottle fly (L. silvarum). On this subject, Mr. Reeks writes that 

 " these flies deposit their eggs in the wool of sheep, generally about the root of 

 the tail or behind the shoulders, anywhere, in fact, where the wool is most greasy. 

 The larvse of these flies are most troublesome to shepherds in the latter part of 

 May and June, until the sheep are sheared, and much later in the summer with 

 lambs, when they should be dipped in a preparation of arsenic and soft soap." 

 Toads and frogs also seem to be frequently selected as objects of attack on the part 

 of these flies. In one case the eggs of a green-bottle fly were laid on a toad's back, 

 and the larvse upon hatching migrated into its eyes. In other cases the laying of 

 the eggs and migration of the larvse have not been actually observed, but toads 

 have been found with their nostrils infested with maggots ; and it is possible that 

 the latter may have effected an entry from the outside, as described above. Mr. 

 Guthrie, who noticed the occurrence of the larva? of a blue-bottle (Calliphora) in 

 the nostrils of toads, writes that " it is probable that the number of toads is largely 

 kept under by those means. In 1872 toads were remarkably plentiful in the 

 neighbourhood of Tenby, South Wales, and I noticed that the disease was very 

 prevalent amongst them. In the following year scarcely any could be found, and 

 I saw none diseased." Cases are also on record of the death of lizards from 

 maggots of blow-flies, which testify to the extraordinary vitality of the latter. 

 In one instance a gecko fed on blue -bottles was found to have the whole 

 abdominal region greatly distended. It soon afterwards died, and on dissection its 

 intestines, lungs, and liver were found to be almost entirely destroyed by maggots, 

 whose presence was naturally attributed to eggs from gravid female blue-bottles, 

 which had been swallowed as food. In another case, some lizards fed on the living 

 maggots of the blue-bottle died in consequence of the attacks on their internal 

 organs by their intended food. Far more important are the cases of infection of 

 human beings ; the resulting sickness, which often entails great suffering, and may 

 end in death, being known as myiasis. 



The sharp-mouthed fly (Stomoxys calcitrans), represented in 9 of the figure 

 on p. G5, closely resembles the house-fly in size, shape, and colouring, but may be 

 recognised by its sharp, horizontally projecting proboscis, and also by the flagellum 

 of the antennas being hairy upon one side only. It is less often seen in houses 

 than the house-fly, although occasionally paying them a visit, especially if there 

 be stables in the vicinity. By means of its proboscis this fly pierces the skin 

 of cattle and horses, or even of man, and gorges itself on the blood. Its eggs are 

 laid in the excrement of the cattle on which it feeds. Resembling Stomoxys in 

 habits and in the structure of its antennas and mouth-parts, the tsetse fly (Glossina 

 morsitans) of Equatorial Africa, although barely equalling a blow-fly in size, is 

 one of the greatest pests to domestic cattle, as the following accounts amply testify. 

 As shown in the annexed illustration, the proboscis of this fly is long and 

 prominent, and the antennae (b) are peculiar in that the third segment is very 

 long and produced almost as far as the apex of the flagellum, which is furnished 

 with barbed hairs along its outer surface only. Writing of the tsetse, Livingstone 

 says that " we had come through another tsetse district by night, and at once 

 passed our cattle over to the northern bank, which, though only fifty j^ards 



