250 



Insect Pests. 



in 1898 many females Avere on the wing as late as the 16tli of 



(Jctober. 



These migratiiio- viviparous females fly back to damson and 

 sloe, but, as stated before, in smaller numbers to other prunes. I 

 have also seen them giving rise to the next generation on hawthorn 

 hedo-es and cherry, but these latter never snrvived. This migra- 

 tion" as far as oljservations go, takes place chiefly on still days and 

 when the air is warm. Tliey do not seem to fly instinctively to 

 the damson, l3ut rather are carried there by chance. Oaks, ash and 

 all manner of trees get covered by the migrants, the majority of 

 whicli could never reach the prunes, and even where a large damson 

 plantation adjoined a hop garden, thonsands of the aphides were 



((4lT;Uly r 



'-I'AMSmN AiMHS. 



,hU-L-.l) 



nio\ing in an opposite direction. Tdie direction of their migration is, 

 it seems, dependent on currents of air — hence hundreds of thousands 

 die, for the ovigerons females do not seem to lie able to live on other 

 trees than prunes. 



These migrants, a few hours after they have become located on 

 their piroper plant, produce a few lice, which grow into ovi]iarous 

 wingless females. It seems that these winged return-migrants 

 pirodnce very few lice, usually only four are produced by each winged 

 female, Imt a few give rise to ii^ e or six. The emliryos can easily be 

 seen in the parent's body. 



About this time winged males also mak'e tlieir appearance. 

 These males are suuiller tlian tlie N\"inged females. They come 



