1902 Ansivers to Correspondents 331 



a grain, the substance of which is just sufficient to support its larval 

 appetite. The disintegration of the grain changes its colour and 

 appearance in no way, so that often a great heap of grain is found to 

 consist of nothing but the worthless husks. These bear the tell-tale 

 hole whence the depredator has made his escape. The beetles require 

 a temperature of more than 50° Fahr. to call forth their activity, which 

 extends in Britain from April to September ; and it has been estimated 

 that a single pair of April beetles will have produced a happy little 

 family of 6045 descendants in the course of the five months. During 

 the winter the beetles desert the corn-heaps and seek warmth and dark- 

 ness in any crevices, holes, folds of sacking, &c., that may be at hand. 



'■'• B. 25. Silvatius sitrinamcnsis^ Linn. — This is another destructive 

 species which has become commonly naturalised in Britain, though its 

 home is obvious. It has upon rare occasions been found beneath the 

 bark of trees in the open country, but usually lies like the preceding in 

 shops and granaries, possessing an even more omnivorous maw and 

 doing much damage to bran, rice, various kinds of corn, dried figs, 

 sugar, &c. 



" C. 19. Lamophlccus fcrrugineiis^ Steph. — This little red beetle 

 pierces wheat grains in granaries and corn-bins with a hole as small as 

 that made by a needle's point ; it is found most destructively in the 

 East Indies, whence it was probably in the first instance imported. It 

 is now quite naturalised with us, and I have several times found it 

 beneath the bark of oak and holly trees, sometimes in small colonies ; 

 it has also been found beneath that of elm. 



"As to the best remedy for these stable pests, the simplest, most 

 effective, and inexpensive for all grain insects is probably bisulphide of 

 carbon, which has recently become of general application both here and 

 in America. This is a colourless liquid with a strong and disagreeable 

 smell ; it is said to vapourise abundantly at ordinary temperatures, to 

 be highly inflammable, and a powerful poison. The most effective 

 manner of application in moderately tight bins consists of simply 

 pouring the liquid into shallow dishes or pans or on to pieces of cotton 

 waste, and distributing these about the surface of the grain. The 

 liquid rapidly volatilises, and being' heavier than air, descends and 

 permeates the grain-heap, killing all insects, as well as any rats or mice 

 it may encounter. The bisulphide is usually applied in tight bins at the 

 rate of i lb. or i ^ lb. to the ton of grain ; whilst in more open bins a 

 larger quantity is of course necessary. Bins may be rendered practi- 

 cally air-tight by coverings of oilcloth, painted canvas, &c. The grain 

 should be left under this treatment for twenty-four hours, but it will be 

 in no way impaired if the period be extended to thirty-six hours. The 

 main drawback to this plan is the poisonous nature of the agent. A 

 thorough floor draught, with frequently whitewashed walls and clean 

 floor, is as good a preventive as can be found." 



J. L. M., Gloucester. 



The passage you refer to, describing the effects on different species 

 of plants and animals caused by the struggle for existence, occurs in 



