230 MAINE AGRICULTURAL EXPERIMENT STATION. I9IO. 



crevices of the bark. All that they do on their return is to bring forth 

 a new brood of little lice. These young develop into the true egg-laying 

 form, male and female. They are wingless and mouthless very small 

 when grown, bright orange in color, and. seem to have no object in life 

 except the deposition of eggs, since they can not eat or fly. The eggs 

 are placed in the deepest crevices of the bark, especially those that are 

 tangential to the tree, and are not easy to find. The small lice perish 

 after depositing eggs leaving only the latter to survive the winter. 



"Last fall the egg-laying brood were abundantly produced on all kinds 

 of trees promiscuously. Their eggs must have been deposited on the 

 same trees, but there is no evidence to show that the young can subsist 

 on any trees but the elm, so it is safe to assume that all on other trees 

 perished. 



"The migration of this louse seems not to have been noticed by 

 other entomologists. It was strikingly apparent last year with us." 



Sanborn (1904) describes carefully and figures the winged 

 form of americana and adds : 



"This form was taken June 16, on the elm (Uhnus americana) . They 

 colonize the ventral side of the leaves, causing them to curl. When 

 numerous they give the leaves a whitish appearance and cause the ter- 

 minal ones to bunch together, which gives the lice more protection. 

 When the leaves begin to turn yellow and look sickly from the yttack 

 of the aphids, the latter are acquiring wings and beginning to migrate. 

 This migration, according to my friend Mr. E. H. Tucker's observation, 

 takes place most conspicuously about twilight, for he says : 'In the twi- 

 light of the evening I took several winged specimens. The air had float- 

 ing in it numerous white insects. After capturing some I noticed that 

 it was a cottony secretion which gave them their white appearance and 

 also sustained them or caused them to be wafted along by the wind'. 

 According to this statement, the flocculent material acts as a sail by 

 which these insects are carried as well as by the aid of their wings." . 



I have observed the migration from the leaf curl in mid-July 

 at Orono. 



In the present paper, the object of which is not taxonomic, 

 this species is treated under the name given it by Riley, although 

 I am of the opinion of Thom.as, who commented in regard to 

 this, "it is doubtful whether it should be considered as dis- 

 tinct"* from nlnii. Professor Gillette (1909) gives americana 

 as synonym of iiJmi of Europe. Perhaps a brief discussion of 

 Riley's reasons for considering this distinctf may not be with- 

 out interest. He states that : 



I. 'Uhni is a longer winged species averaging 7.3 mm. in 

 expanse.' (Absolute size can hardly be held a specific distinc- 



'TRiley and Monell on Aphididae. p. 

 *Thomas III Report, page 204. 187c 



