327 
HYDROBIUS FUSCIPES; 
NOTES ON ITS LIFE-HISTORY, LARVAL ANATOMY, ETC. 
WALTER F. BAKER, F.E.S., 
Whitkirk, Leeds; late Hon. Secretary of the Yorkshire Naturalists’ Union. 
THE following is a brief account of the life-history of one of our 
common aquatic beetles, and is given, not only as a contribution to 
entomological literature, but also in the hope that it will induce 
others to pay more attention to the life-histories of the various 
creatures whose distribution they are studying. I have no intention 
of under-rating the work done by the systematist—far from it—for 
the facts of distribution are quite as important in their way as any 
other facts, and throw light upon many points that would otherwise 
be obscure ; but my meaning is, that instead of naturalists devoting 
their whole time to enlarging their collections and studying the 
distribution of insects in their own particular neighbourhood, they 
should extend their researches into the equally attractive and less 
known study of life-histories. Another class of naturalists who 
might with advantage turn their attention to this branch, is the 
So-called microscopist, who, whilst possessing a good instrument and 
the usual accessories, yet contents himself with buying his slides, 
and is always ready at a wie ae conversazione to show th 
ever-present stock objects, such as ‘wing of butterfly,’ ‘diatoms,’ or 
the ‘human flea.’ Very little is known of the early stages of many 
of our commonest insects, and though it necessitates constant and 
careful watching, yet it is a Ge a easy branch of natural 
history, and will well repay the student. 
This little beetle, Hydrobius fuscipes (Fig. 1), is one of the 
commonest, if not the most common, of our aquatic beetles. It 
varies very —— - ages? ows in ane 
marshes of 
I have often i auat arena measuring as 
much as 8 mm. in length, but most of the speci- 
mens I have obtained in Yorkshire are not more 
than 64 mm., and they are occasionally found less — 
still. It is hardly possible that this is owing to 
climatic distinctions, as the difference is so slight, We 1. 
neither is it owing to scarcity of food, for though Hydrobius fuscipes x 3 
the fens of Lincolnshire may be a more ideal spot for it than the 
more thickly populated and less marshy county of York, yet there 
cannot be any real insufficiency of food, for it is not at all particular 
in this respect, and I have kept them alive for nearly a year by 
feeding tl them on nothing but —— Whether they are entirely 
Nov. 1804. 1894. 
