332 MAINE AGRICULTURAL EXPERIMENT STATION. I916. 



Mr. A. C. Baker of the Bureau of Entomology wrote me (Nov. 20, 

 1912) : "I found that when the colonies are very thick the alate forms 

 often stay on- the apple and I have found on one tree a number of 

 winged ones with the abdomen shriveled as it is after producing sexes. 

 I saw some sexes crawling up and down the small twigs and though 

 I have not yet seen any eggs which they laid they no doubt would 

 lay eggs. On one occasion I found sexes on an apple leaf which had 

 fallen to the ground." 



That such occurrences are not a part of the ordinary life 

 cycle is indicated by the usual wholesale flight of the fall mi- 

 grants.* 



On the elm the stem mother, which hatches from the over- 

 wintering eggs sheltered probably in rough crevices of the bark, 

 appears early in the spring and may be found in Maine before 

 the middle of May stationed on the partly opened leaf buds. 



The beak punctures on the rapidly expanding new leaves 

 cause an unevenness of growth which forms a protection for 

 the aphid. By the last of May the earliest of these wingless 

 stem mothers are mature and found in the deformed elm leaves 

 (Fig. 59) producing the next generation. The antenna is 

 shown in Fig. 68. 



These nymphs, like the stem mother, are a wingless form and 

 they become fully developed about the tenth of June. They have 

 wax glands, of the type shown in Fig. 61. Their . progeny are 

 the third generation and attain wings. These winged aphids are 

 known as the spring migrants. 



It takes three weeks or slightly more or less, beginning about 

 the twentieth of June, for all the individuals of this third gen- 

 eration to get their growth so that the migration covers a con- 

 siderable period. The deserted rosette or leaf cluster at this 

 time looks like Fig. 60. During this time these winged aphids 

 may be found alighting on the leaves of apple, mountain ash, 



*I904. Alwood, Wm. B. Circular in Relation to Some Injurious 

 Insects and Plant Diseases. Special Bulletin (C. P. C. 45), Va. Exp. 

 Sta. 



1908. Gillette, C. P. Notes and Descriptions of Some Orchard Plant 

 Lice, of the Family Aphididse. Journal of Economic Entomology, Vol. 

 1, pp. 306-308. 



1909. Borner, Carl. Kaiserliche Biologische Anstalt fur Land-und 

 Forstwirtschaft, August. 



1913. Reh, L. Der Praktische Ratgeber im Obst — und Gartenban, 

 February 2. 



