236 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 4 



entire season and it is evident from the length of life occasionally 

 found that a single generation might span the entire season. 



Mortality. — This appears to be greatest during the coldest part 

 of the winter season, when large numbers of the adults, as well as 

 many of the immature stajges, die. Accordingly, in March, after an 

 average winter in this locality, but 14 per cent of either immature 

 stages or adults were found alive. 



In the field, during the fall, largest mortality appears to be with eggs 

 and young larvse. There is also considerable mortality during the 

 propupal stage and with adults in the act of emergence. 



Parasites are not uncommon and two or three species have been 

 bred from immature stages of the weevil. 



Parthenogenesis: — It is interesting to note that we have found 

 strong evidence of the common occurrence of parthenogenesis among 

 rice weevils. Unfertilized females deposit eggs occasionally but much 

 more rarely than is normal. Many observations have shown that 

 these eggs may hatch. We have bred a male and a female weevil 

 from eggs deposited by a positively unfertilized female. Their devel- 

 opment required about five months, from October to March, in a 

 heated room. 



INJURIOUS INSECTS OF 1910 AT TREESBANK, MANITOBA 



By XoRMAN' Criddle 



The areas covered by this paper contains most of the types of soil 

 found within the Province of Manitoba and a fair percentage of the 

 kind of crops grown. It also embraces open country and woodlands 

 of different sorts, so that, on the whole, we might expect to find within 

 its borders most of the insect pests that inhabit other portions. 



Owing to an exceptionally dry season cereal crops were, generally 

 speaking, very poor and this made the inroads of some insects, notably 

 grasshoppers, much more difficult to control than they would otherwise 

 have been; it also caused several pests of importance to be overlooked, 

 the poor condition of grain being generally put down to unfavorable 

 weather conditions. 



Insects Injurious to Grain and Grasses 



Hessian Fly, Mayetiola destructor. — Injury was reported to be 

 rather extensive in some localities but investigation did not bear out 

 the reports, but revealed that most of it was due to other insects. 



The Greater Wheat-Stem Maggot, Meromyza americana. — This 

 and probably the Lesser Wheat-Stem Maggot {Oscinis carbonaria) 



