68 
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 larvae 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 larvae upon hatching migrated into its eyes. In other cases the laying of 
the eggs and migration of the larvae 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 larvae 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. 65, 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 antennae 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 antennae 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 ( h ) 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 onl}". 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 yards 
