[Xoven r, 
134 
tenna and tte upper apical portion of the posterior femora pitchy-bla k, 
and the suture very slightly rufescent; whilst in the darkest, the an- 
tennse, head, posterior femora almost entirely and anterior and middle 
femora slightly, apex of all the tibise and tarsi, and the suture (especiaUy 
behind), are pitchy. This darkness, however, I suspect must principallj 
be attributed to a mere suffusion of fluids in drying after death. 
7, Park Field, Putney, S.W. : Uth October, 1868. 
ON THE ABUNDANCE OF CERTAIN INSECTS IN CERTAIN YEARS. 
BY B. C. S. JOEDAJf, M.D. 
It was formerly a favourite hypothesis with me that either the eggt 
or pupffi of some insects lay dormant until a favourable season for theii 
development ; but I am growing more and more weaned from this idea 
yearly. I do not wish to deny that the pupae of Eriogaster lanestris, 
for example, may pass over a year when February and March a« 
unusually bleak, but this latent state is not the reason for the periodic 
abundance of certain insects. Every moth lays a vast number of eggs 
and generally the greater number of these perish before arriving ai 
maturity, the usual time for such destruction is probably the very younf 
stage of larval life, and a heavy rain about that period may cause grea 
mortality ; in some years all circumstances prove favourable, and th( 
usually rare insect becomes abundant. Some lepidopterous insects ar 
peculiarly subject to this periodic plenty, such as Colias JEyale am 
Edusa (both IbeHeve always abundant on the continent). Sphinx convol 
vuli, Agrotis saucia, insects of the genus ReliotMs, and many otheri 
These remarks have occurred to me " in populous city pent," and wit 
too much work to touch entomology for the season, from the unusu£ 
abundance of two insects in the streets of this town. They have bee; 
Ghrysopa perla and Coccinella septempunctata. Of the former I counte 
more than twenty on each of two consecutive lamps one night, an 
every other lamp seemed to have an equal number ; as for the latte 
they have been so plentiful that I have seen children of ten collectm 
them from the walls in little baskets and paper bags. Now it is we 
known that the larva of these two insects are subject to very simili 
conditions as far as regards the general " struggle for existence," widel 
different as the perfect states may be. These few remarks are given ; 
the hope that some interesting observations may be drawn out fro 
entomologists as to their experiences during the very peculiar ar 
almost tropical summer through which we have just passed. Syrph 
pyrastri has been only a little more plentiful than usual. 
35. Harborne Road, Birmingham: Sept. 12th, 1868. 
