Entomological Society. 5765 



afforded more food for reflection, and in 1852 I sacrificed a number of Sphinx Ligus- 

 tri and our of three species of Smerinthus, thinking to find and investigate a similar 

 phenomenon. In this I was disappointed : all the specimens were summer-dis- 

 closed, and all had the ovaries distended with mature eggs. I was now inclined to 

 assume that the previously observed facts were accidental or exceptional, and not to 

 be recorded as the results of any universally operating law ; but, last autumn, that is 

 the autumn of 185(>, the subject was again brought before me by the examination of 

 recently disclosed females of Acherontia Atropos, which proved perfectly sterile. 

 Now, as I knew there was a summer disclosure of this insect, giving rise, among the 

 raw recruits of our science, as in the case of hybernating Rhamni, to a double-brooded 

 hypothesis, I could not but be struck with a phenomenon that began to assume the 

 weight and importance of a fixed law. It appeared, on comparing and arranging a 

 series of observed facts, 1st, that certain Lepidoptera had two periods of disclosure, 

 the aestival and the autumnal ; that the summer batch, produced while the leaves were 

 in full vigour and afforded abundant food for the larvae, was fruitful; the autumnal 

 brood, disclosed when the leaves were about to fall, was barren. The autumnal brood 

 seems only to occur in cases where the number of the specimens has been much larger 

 than usual, and when the species, if multiplied by uniform and ordinary fecundity, 

 would either more than exhaust the usual food-plant, and would therefore starve, 

 or would seek other food, and thus defoliate our vegetation. The phenomenon, there- 

 fore, if reduceable to a law, is yet another proof of that ' wisdom of God in creation ' 

 which was the favourite theme of our greatest English naturalist, and the illustration 

 of which is the cherished object of every right-minded teacher at the present day. 

 Before offering these remarks to the Entomological Society I thought I would sub- 

 mit the facts to the scrutiny of a second entomologist; and for this purpose I selected 

 the ' Lepidopterologiae Princeps' at once, thus passing by, not only the habitues of 

 what might be called our ' Circumlocution Office,' but also those really hard-working 

 investigators of truth, our Wollastons, our Douglases and our Powers. Mr. Double- 

 day's experience, I am happy to say, exactly coincides with my own. The following 

 extract from his letter contains irresistible evidence of the prevalence of my facts: — 

 ' The first pupa,' Mr. Doubleday writes, ' that I ever possessed of Acherontia Atropos 

 produced a female moth, in July, and was full of eggs. In 1846 I had a number of 

 larvae of the same species ; these became pupae at the usual time, and eight or ten 

 moths were produced at the end of September or beginning of October ; all the 

 females we're barren, their abdomens being quite hollow. Most of the female Cou- 

 volvuli that I took the same year [it was the great Convolvuli year] were barren, but 

 I took one or two which laid eggs; not one of the eggs, however, hatched. I believe 

 the females of some species are mostly barren when disclosed in the autumn ; but 

 where there are two distinct broods of a species, a vernal and autumnal brood, both 

 are fertile. I believe that all species occasionally produce barren females.' " 



Mr. F. Smith read the following extract from a letter addressed to him by Mr. R. 

 T. Grant, from Canada West (Oiillia):— 



Letter from Mr. R. T. Grant, West Canada. 



" The first insects make their appearance about the middle of April, on the blos- 

 soms of the sallows, which are very plentiful here, and swarm with insects of all 

 orders, even before the snow has disappeared. Fancy the ground covered with snow 



