— so- 

 weather were dry and their food nourishing they would increase steadily at a 

 geometrical ratio. After a year or two or three of drought the intelligent farmer 

 will be more watchful for the first appearances of insect outbreak than after a 

 series of unusually wet years." 



Heavy rains may eft'ect direct mechanical or physiological injury by beating 

 to the ground and drowning many insects especially in the younger larval stages. 

 A rainy season may also indirectly exert a pathological influence in diminishing 

 the numbers of certain insects, by bringing about favourable conditions for the 

 spread of furgous parasites of these insects. So it is likely that a very wet season 

 will always act as an inhibiting factor in the general increase of insect pests. 

 On the other hand, a dry season, not dry enough to prevent the growth of their 

 food plants, is conducive to the abundant multiplication of insect pests, especially 

 those with two or more broods. It must be remembered however that conditions 

 favourable for the development of injurious insects — viz., optimum nutritive and 

 climatal environment — are also favourable for their parasites. Thus last year, 

 while there was an abundance of certain harmful forms there was also a marked 

 abundance of predaceons and parasitic insects. 



Melanotus cribulosus: The Corn Wirewonn; a, adult beetle; b, wireworm or larva; c, last segment of larva. 



Ciitzi'ornis, wire-zvorms and white grubs were all found in the soils of the 

 college farm, but with the exception of two species of wire-worms did not do 

 very much harm. These wire-worms were the larvae of Melanotus communis 

 and Agriotes mancns which were responsible for the destruction of much seed 

 corn sown in a field that followed sod. Melanotus communis was the most com- 

 mon wire-worm observed both in the larval and the adult stages. Both of the 

 above species, as well as others, were observed in the sod lands. 



