INDIRECT INJURIES CAUSED BY INSECTS. 177 



snal ; and we cannot wonder that a creature so prolific 

 should be proportionably injurious: some species, how- 

 ever, seem more so than others. Those that attack 

 wheat, oats, and barley, of which there are more kinds 

 than one, seldom multiply so fast as to be very noxious 

 to those plants ; while those which attack pulse spread 

 so rapidly, and take such entire possession, that the 

 crop is greatly injured, and sometimes destroyed by it. 

 This was the case with respect to peas in the year 

 1810, when the produce was not much more than the 

 seed sown ; and many farmers turned their swine into 

 their pea-fields, not thinking them worth harvesting-. 

 The damage in this instance was caused solely by the 

 Aphis, and was universal throughout the kingdom, so 

 that a sufficient supply for the navy could not be ob- 

 tained. The earlier peas are sown, the better chance 

 they stand of escaping, at least in part, the effects of 

 this vegetable Phthiriasis. — Beans are also often great 

 sufferers from another species of leaf-louse, in some 

 districts from its black colour called the Collier^ which 

 begins at the top of the plant, and so keeps multiply- 

 ing downwards. The best remedy in this case, which 

 also tends to set the beans well, and improves be'th 

 their quality and quantity, is to top them as soon a'^ the 

 Aphides begin to appear, and carrying away t'.^e t^pg 

 to burn or bury them. — In a late stage of grr^wth o-reat 

 havoc is often made in peas by the gru*^j of a small 

 beetle, (Bruchus granajius^ L.,) which will sometimes 

 lay an egg in every pea of a pod, ar^d thus destroy it. 

 —Something similar I have been t old (I suspect it is a 

 short-snouted weevil) occasioni'jly injures beans. In 

 this country, however, the mischief caused by the 

 Bruchus is seldom very sevious ; but in North Ame» 



TOL. I. N 



