232 OBSERVATIONS ON INSECTS. 



The greasing of insects in cabinets is a circum- 

 stance well known to every collector. I am not 

 aware, however, of its having been observed, that the 

 males, at least among the Lepidoptera, grease much 

 more frequently than the females. Such at any rate 

 is the case in my own collection, in which, in the 

 instance of the following species more especially, I 

 find the male specimens alone affected: Smerinthus 

 ocellatus, Sphinx ligustri, Macroglossa stellatarum, 

 Hepialus humuli, Zeuzera cesculi, Cossus liyniperda, 

 Cerura vinula, Saiurnia pavonia minor, Lasiocampa 

 quercus, odonestis potatoria, Gastropacha quercifolia, 

 Dasychira fascelina, Leucoma salicis, and Spilosoma 

 lubricipeda. 



I think also, I observe, among the Coleoptera, that 

 the timber-eating beetles, such as the Lucani and 

 the Cerambycidce, grease more (contrary to what one 

 might have expected) than those which, in the larva 

 state, feed on animal substances. But possibly a 

 more extended inspection of other cabinets might 

 prove this last remark not generally confirmed. 



It was once remarked to me by an eminent philo- 

 sopher, who thought nothing in nature beneath his 

 notice, that, having had the curiosity to analyze the 

 excrement of the common silkworm, he was much 

 struck with finding how little change had taken 

 place, in the portions of the leaves which these 

 caterpillars had devoured, by the process of diges- 

 tion. This induced me to examine the excrement of 

 several species myself. The dung of a full-grown 



