Report of the State Entomologist. 



61 



Its Abundance at Lake Pleasant, N. Y. 

 During July and August last they were observed in large numbers 

 at Sageville (Lake Pleasant), Hamilton county, N. Y. To many of 

 the trees they imparted a peculiar nodose aj^pearance, in instances 

 where they abounded to such an extent that at least three-fourths of 

 the leaves of the tips of the season's growth bore the gall. At this 

 time each contained its larva, which but partially filled the gall, yet 

 appearing as if it had nearly attained its growth. The larvae, when 

 exposed lo examination, were inactive, hardly showing any motion, 

 and giving no evidence of a disposition to feed. 



The Gall Described. 

 The gall consists of an oval enlargement of the leaf near its base, 

 varying in posi- 

 tion from entirely 

 basal (rarely) to 

 one-fifth of an inch 

 removed (also 

 rarely); the aver- 

 age distance does 

 not exceed 0.05 of 

 an inch. The aver- 

 age length of the 

 gall may be some- 

 what above one- 

 eighth of an inch, 

 with a diameter 

 two-thirds as 

 great, which sel- 

 dom exceeds twice 

 the width of the 

 leaf. Its elevation 

 above the surface 

 of the leaf is about 

 equal on the two 

 sides, although 

 sometimes seem- 

 ing more depress- 

 ed superiorly from 

 the bending of the leaf by its defoi'mation forming a concavity 

 above. The exterior of the gall is smooth, except as showing some 

 trifling irregularities of growth. 



Fig. 28. —Balsam tip with galls of Cecidomyia BALSAincoLA: 

 a, leaf enlarged with gall seen on upper side ; I), the same with 

 gall from lower side, with opening for escape of the larva; 

 c, leaf from which the larva has escaped through opening on 

 upper side. 



