PLANT LICE. 203 
produced upon the hop, until during September winged females 
appear. ‘These are called “return migrants,” as they return again 
to the plum. Each of the females produces three or more young 
lice which never become winged, yet are true sexual females, 
Fic. 160—Winter-eggs on plum. Fic. 161—Phorodon humuli Schrank. 
Original. —Stem-mother, enlarged, head 
and antenna still more enlarged. 
After Insect Life, Div. of Entomol- 
ogy, Dep. of Agriculture. 
Fic. 162—Phorodon humuli Schrank.—First migrant from plum, third genera- 
tion, enlarged; head at side still more enlarged. After Insect Life, Div. of En- 
tomology, Dep. of Agriculture. 
