414 



Grain Weevils, 



[OCT., 



moisture present in the grains themselves, C. granaria will 

 live a long time and will copulate and lay eggs. In an 

 experiment with 24 C. granaria kept in such tubes in a 

 sitting-room that had a fire in winter, some of the beetles lived 

 for nearly 14 months ; there was no hibernation in the winter, 

 and 7! months passed before the first beetle died. Eggs 

 were laid in every month of the year. Four such tubes 

 from which the weevils that had laid eggs in the grain had been 

 removed, were kept securely corked for 9 months. The tubes 

 showed at the end of this time frass and moisture and mouldy 

 grains. Each tube held weevils that had developed from the 

 egg stage in the enclosed grain. These weevils were counted 

 and numbered in the four tubes respectively, at the end of 

 9 months, 67, 80, 81 and 134, a number of them being alive. 



The Calandra weevils on being touched or shaken feign death ; 

 they lie, often for a considerable time, refusing to show any 

 signs of life though handled. I found that one could induce 

 movement by breathing on them. 



Remedial Measures. — (1) Fumigation with bisulphide of 

 carbon is a very satisfactory way of ridding grain of the 

 insects. The grain to be treated should be put in a bin or air- 

 tight receptacle, and the bisulphide of carbon poured into a 

 saucer or shallow vessel and laid on the top of the grain. The 

 liquid volatilises readily and the fumes, being heavier than air, 

 sink down through the grain and kill all insect life ; 1 lb. of 

 bisulphide of carbon is sufficient for 100 bushels of grain. The 

 air-tight receptacle should be kept closed for 24 or 48 hours. A 

 shorter time would do for small quantities of grain. In disinfect- 

 ing a store or mill, 1 lb. of bisulphide of carbon is sufficient for 

 every 1,000 cubic feet of space. Before entering the mill 

 after such fumigation the doors and windows should be thrown 

 open for an hour or two in order that the place may be well 

 ventilated. 



Bisulphide of carbon has a very disagreeable odour and as the 

 fumes are poisonous they should not be breathed, though 

 a little will do no harm. It is also explosive, so that a naked 

 light should not be brought near it. 



Sieving or Screening. — (2) Infested grain may be run through 

 a sieve or a screen, the meshwork of which is sufficiently fine to 

 keep the grains back and yet let the weevils fall through, 



