133 



be done in EDgland, I may briefly state that on account of the cooler 

 summers and milder winters and the hiteness at which wheat is sowu 

 in England there is very little danger, in my judgment, of any such in- 

 jur\^ as we snfler from here, or as the insect causes in portions of con- 

 tinental Europe. lu fact it is very injurious only under conditions 

 where two annual generations are pretty uniformly produced, and I am 

 satisfied that in England, as a rule, only one generation will be pro- 

 duced. 



THE HOP PLANT-LOUSE. 



The next insect which I will say a few words about is the Hop Plant- 

 louse {Phorodon humuli), of which we have been able to say for the first 

 time the past year that we now know positively its full life history. I 

 have for some years desired to settle a question that has been mooted 

 aoiong entomologists, as also among hop-growers, viz, the mode of 



hibernation of the species ; for while some 

 of the earliest writers upon aphidology have 

 believed, and eveu stated, that there was a 

 form of this insect tha^t occurred in autumn 

 on the Damson in Europe, the statement has 

 been as confidentlv controverted and the 

 fact denied by some of the highest author- 

 ities in the family. Hop-growers as a class 

 have generally i^ooh-poohed the idea. Yet, 

 from my own experience with other species 

 of the family and with their singular life 

 history and migrations from one plant to 

 another, I had for some time felt convinced 

 -FiG.so.phorocionhumuii.siem.mothev, that FJioroclon humuU also must have some 



enlarged, head and antenna still more 



enlarged (original). othcr Winter resting place than the hop vine, 



Fig. 31. Phorodon htimuli, first migrant from plam, third generation, enlarged ; head at side still more 



enlarged (original). 



