INSECTS 



The geographical position of Cornwall does not appear to have so much 

 influence on its insect population as upon its marine life and its birds. In 

 common with the other southern counties of England, it possesses a number of 

 insects with a very limited range to the north, but neither in wealth of species 

 nor in pride of peculiar possession is it greatly distinguished from the adjoining 

 counties. The width of the Channel no doubt diminishes the number of casual 

 but exciting visitors from the Continent, though at Falmouth, Penzance, and 

 occasionally elsewhere aliens ' of assisted passage ' are taken from time to time. 

 There is evidence now and again of immigration on the south coast sometimes 

 on an extended scale, but migratory movements seem to be much more frequent 

 on the Bristol Channel side. At Bude, Mawgan Forth, Hayle, and elsewhere 

 on the north coast a long fringe of black scum has been occasionally observed 

 on the advance water of the inflowing tide or else a crape-like band on the 

 sand at high-water mark, which on examination is found to consist of millions 

 of drowned insects, presumably overtaken by adverse weather when en route, or 

 blown out to sea by sudden storm. At Chapel Forth, St. Agnes, and at 

 Mawgan Forth in the vale of Lanherne, an irregular stream of insects has been 

 occasionally observed for hours at a stretch passing steadily out to sea, some- 

 times in large flocks, sometimes in twos and threes, never showing undignified 

 haste, but rarely loitering much before their departure. When cabbage whites 

 are abundant this emigration stream becomes very conspicuous, and hundreds 

 of thousands of these butterflies must at times in the course of a single after- 

 noon pass out of the county to the north at Chapel Forth. As drowned butter- 

 flies have never been reported in quantity along the north coast, it would 

 appear that most of them effect a landing somewhere. There is little direct 

 evidence to show that immigrant swarms come in on the Bristol Channel coast, 

 but the number of waifs and strays from more northern localities, especially 

 among the Lepidoptera, that are from time to time captured in Cornwall, 

 certainly suggests movements of this kind. 



The remarkably genial climate of Cornwall might have been expected to 

 favour the presence of a few specially southern insects, particularly round the 

 head of Mount's Bay, but so far as known there are none peculiar to the 

 district, and, indeed, the specially Cornish insects favour the north coast rather 

 than the south, and the most obvious effect of the mild winters is to disturb 

 the rest of hibernating species and hasten the appearance of some that emerge 

 in the early spring. 



In some orders, and notably in the Lepidoptera and Coleoptera there is a 

 marked scarcity of insects throughout the county, and the number of species 

 recorded is no index to the density of insect population. In both the orders 

 named a much greater proportion of species than usual is represented by only 

 one or two specimens, and if these casuals were removed from the lists there 

 would be a very considerable shrinkage in their dimensions. 



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