1876 .] Nature's Scavengers. 165 
the nicety with which a wasp snatches away flies from such 
nuisances without soiling its feet or wings. 
Among the Orthoptera, Neuroptera, Homoptera, and 
Hemiptera there are no true scavengers. The Diptera, on 
the other hand, feed to a very large extent upon carcases 
and foecal matter, and many of them may at first sight be 
taken for scavengers of great efficiency. There are very few 
of the Muscidse — the family including the common house- 
fly — which do not, at one part of their lives, feed upon dung, 
carrion, or decomposing vegetables. Thus the blow-flies, 
Lucilia Cczsar and Calliphova vomitaria, like the Silphce and 
Necrophori , deposit their eggs in dead animal matter. But, 
unlike the beetles just mentioned, they neither bury the 
substances containing their eggs nor do they restrict their 
attacks to tainted meat. Their ova and larvae possess a 
remarkable power of setting up and intensifying putrefaction 
in any animal matter with which they come in contact. 
Even living animals are not exempt from the attacks of these 
and allied species, which take every opportunity to lay their 
eggs in open wounds or abrasions of the skin. These flies, 
also, after being in contact with the most loathsome sub- 
stances, settle upon man’s person and on his food. Now 
how minute a portion of putrid blood, pus, &c., may set up 
dangerous changes in articles of diet, or may serve as the 
vehicle of disease, we do not exactly know, but we have 
reason to believe that exceedingly small quantities will 
suffice. Very similar charges must be brought against the 
house-fly ( Musca domestica), the privy-fly ( Anthomyia canicu- 
laris ), and the blood-sucking Stomoxys calcitvans. All these, 
and many more indeed, at once consume nuisances and 
propagate them. The proboscis of a Stomoxys thrust into 
our flesh has perhaps, a moment before, been saturated with 
morbid matter, and the result of its bite may be carbuncle. 
Ophthalmia is certainly propagated by flies, and a closer 
examination will doubtless prove that variola, typhus, black 
vomit, scarlatina, and zymotic disease generally are spread 
about in the same way. Hence it is of the greatest im- 
portance that the dejections of patients suffering from such 
diseases, the bodies of the dead, and every substance which 
can have imbibed the morbific matter, should be treated in 
such a manner that these minute harpies may be prevented 
from settling and feasting upon it. The open cesspools 
attached to privies in country places are often one wriggling 
mass of maggots, and seem to call loudly for a liberal dose 
of carbolic sulphite, or some other enemy to low forms of 
life. It is in such localities that the attack must be made. 
