426 THE BIOLOGY OF INSECTS 



belladonna and pyrethrum), cayenne pepper, and other 

 apparently unpromising materials. One species, Lasioderma 

 serrtcorne, a native of North America, indulges, according 

 to G. A. Runner (1919), in all this wide range of feeding 

 habit, but it has lately become increasingly notorious as the 

 *' Tobacco Beetle," as it has tended more and more to 

 specialise on the prepared products of that plant, which is 

 even by its human devotees not generally classed as 

 nutritious. Lasioderma feeds indifferently on " cured 

 leaf tobacco, smoking and chewing tobacco, snuff, cigarettes, 

 and cigars." Through the closely rolled dried leaves of 

 the last-named articles of luxury the whitish soft-coated 

 grubs of the insect bore their way, and the adult beetles, 

 their transformations complete, come out at the surface 

 through neat circular '' shot-holes." It is reckoned that 

 through such damage to cigars a sum approaching ,£50,000 

 is lost yearly in the PhiHppines alone, and ,£5,000 was 

 reported as the annual loss due to the beetles, suffered by a 

 large tobacco business in the United States. Another 

 firm had to discontinue the production and export of cheap 

 cigars worked up from *' scrap tobacco," because, through 

 the destructive action of the beetles, a large proportion of 

 the shipments were returned, though at the inception of 

 this department of the business the profits made by it had 

 amounted to $7,000 a year. It is evident that the constant 

 transport of a widely used commodity, such as tobacco and 

 its products, must facilitate the extension of any insect 

 that feeds on these substances, and the great masses of 

 material housed in a confined space favour the creatures' 

 rapid multiplication. With stored products as with field- 

 crops, the actions of man himself tend to induce such 

 quick reproduction of adaptable insects with plasticity of 

 behaviour that they inevitably become pests. Then 

 civilised man seeks to re-act to the loss that he suffers by 

 attacking the destructive insects with all effective weapons 

 from the armoury of modern science ; and expensive 

 machinery or apparatus is installed in order that thousands 

 of little beetles and their grubs may be frozen under cold- 



