AXD OTIIKR INJURIOUS INSECTS OF I907 AND I908. 47 



THE ENGLISH GRAIN LOUSE. 



Macrosiplnii'i granaria Buck. 



The following additional notes on this species have been taken 

 this summer. For the work of 1907 the reader is referred to Bulletin 

 No. 108 of this Experiment Station : 



The complete life history of this louse so common in our grain 

 fields has not been worked out, and it is a problem assigned to the 

 Minnesota entomologist by the Department of Agriculture at Wash- 

 ington. At least another season will be required to obtain final results. 

 Our findings show very conclusively the varieties of food plants 

 affected, its very general distribution over the state, the hardiness of 

 the species (indicated by our finding viviparous females with young 

 on December 10th),* the probable first appearance of winged migrants 

 by means of which the species is principally scattered, and the amount 

 of parasitism, upon which we largely depend to keep this pest in 

 check. 



In considering the following notes one should bear in mind the 

 method of reproduction of all of tlicse aphids, viz. : A "stem mother" 

 hatching in the spring from an Qgg which has gone through the 

 winter then from ten to twenty generations (approximately) of 

 females, some of which are winged ("migrants"), and no males until 

 fall, at which time, and only then, mating takes place, and eggs are 

 laid (the only eggs in the series) which will hatch into stem mothers 

 the following spring. 



General suggestions for the control of all grain aphids will be 

 given at the end of this article. 



December 19, 1907. Winged and wingless viviparous forms 

 found at Experiment Station on plots of winter wheat and on rye. 



December 22. No sexual forms ; a few winged forms found on 

 the above plots. At least one-half of the lice found were dead. This 

 would seem to indicate that the sexual form appears very late in the 

 season. 



January 19, 1908. No lice found on winter wheat. Temperature 

 at time of examination 40 degrees above zero. Has been below zero 

 only twice during the winter up to this date, the thermometer register- 

 ing en an average from 18 degrees to Z2 degrees. 



February 15. No live aphids and no eggs found on experimental 

 plots of winter wheat. 



April 23. A young (nymph) found on grass. 



*The same observation made Dec. lOtli, 1908, at which time no eggs could be found. 

 The temperature has been as low as —5° F. for a short period. 



