fnsects. 4849 



the months of February and March. Many of us have forgotten that 

 these insects are far better protected against the rigours of frost than 

 we are ; and so, by following the old-fashioned custom of collecting 

 only when the sun shines, we fail to obtain probably many species 

 which are now either of the rarest, or altogether unknown. 



So far as we know, there is but one of our native species that is 

 eminently nocturnal in its habits — Orectochilns villosus. 



I have been making, during the summer, some experiments as to 

 the practicability of keeping these insects in vivariums ; and have 

 succeeded, at least so far as to be able to recommend the subject to 

 any who would desire to enter upon an untrodden field of research, 

 or even to those who would view vivariums merely as interesting 

 subjects for their drawing-room windows, 



I believe that a careful study of these groups when alive, and when 

 subject only to conditions which affect their natural state, will reveal 

 to us very much of their habits, of which we are now so confessedly 

 ignorant : we know nothing of the period of their larva and pupa 

 states, of their metamorphoses, of their distinctive specific habits ; 

 nay, we are unable to recognize the insect at all as a pupa or larva. 



All this and much more has to be learned ; and all this and much 

 more may readily be discovered by any who will give a little patient 

 attention to the subject of vivaria. I have no doubt whatever that it 

 is within the power of almost any one of your readers to throw much 

 light upon these very interesting questions; and this, not by devoting 

 himself entirely to the study, but as an amusement, by merely 

 attending to the natural requirements of the species, keeping up a 

 proportionate supply of vegetable life, spending a few minutes de die 

 in diem in watching them, and carefully recording on paper, which 

 should always lie near the vivarium, whatever he sees with his 

 eyes. 



I have throughout the following catalogue noted the size of each 

 species in French millimetres ; I have done so because, in the absence 

 of specimens, I found it very difficult to give their exact value in 

 lines without either producing unwieldy fractions, or deviating from 

 strict accuracy ; I have hence followed the Continental system of 

 measurement. 



Genus Dytiscus. 

 (D. latissimus, Linn., Fab., Oliv. Long. 40; larg. 25. The largest 

 of the genus, known at once by its largely-dilated elytra; not un- 

 common in northern countries of Europe. Rare in France.) 



