Cooke: 0:s Scarcity and Abundance in Insect Life. 183 



I can well remember the wet summer of 1860. I was living at 

 Manchester then, and for about three weeks together there was one 

 dull, impenetrable cloud hauging over the town, with heavy rain 

 almost daily. The consequence of this was, that in the following year 

 there was scarcely a butterfly to be seen within a range of seven miles 

 from Manchester Exchange. I saw one meadow-brown and one or 

 two white butterflies, and the next year was not much better. Is it' 

 too much to say that the main cause of this scarcity was the impossi- 

 bility of the larvae obtaining dry food ? 



In the case of Charceas gramitiis above mentioned, it was afterwards 

 stated that the larvae had been greatly diminished by crows and gulls, 

 and that this clearance had also been helped by the rains. On this 

 latter assertion being questioned, Mr. Axon, of Manchester, says that 

 his informants held that the rain had considerable influence, and he 

 quotes Kollar, " On Insects injurious to Gardeners," who says : — 

 " Continued rains, particularly when they occur about the last time of 

 the caterpillars changing their skin, are suflicient to destroy them 

 entirely, as was the case in the Harz territory." I ask, is not this 

 because their food was spoiled at this critical period of their lives 



It is needless for me to occupy your time by examining in detail 

 the ways in which excess in insect life is kept down by their numerous 

 enemies, I need only allude to the fact of their being a prey to 

 multitudes of birds, also of fishes and reptiles ; that there are numerous 

 predaceous insects which prey upon other insects, in the orders 

 coleoptera, hymenoptera, diptera, neuroptera, and a few in the orthop- 

 tera and hemiptera ; and that the bulk of the hymenoptera live at the 

 expense of other insects, their larvae feeding upon other larvfe. Indeed 

 the restraints on excessive abundance are so numerous and powerful^ 

 that the wonder is it should ever exhibit itself. 



A very interesting feature in the question, and one that is most 

 difficult to account for, is the occasional appearance, in some numbers, 

 of a species generally considered scarce, such a visit being also of a 

 local and transitory character. An instance of this is familiar to most 

 of our members. In the year 1870 several hundreds of the larvae of 

 Deilephila galit were found feeding on Galium verum growing among 

 the sandhills on the Cheshire coast. I believe, previous to that year, 

 that no published record existed of the occurrence of this species in 

 the locality, and that no captures of it in Cheshire have been recorded 

 since. In this case it certainly cannot be said that the lepidopterists 

 of Liverpool and its environs do not know when or how to find it, 

 though it may be very true that they do not know tvhcre. It is only 



