NEW YORK STATE MUSEUM 



103 



insect seems to be local in habit, since clusters of slippery elm 

 sprouts are very likely to have a considerable proportion of the 

 buds blasted by the work of this midge. The infested buds expand 

 to a varying degree, the green leaves just pushing out of the dark- 

 brown bud scales in some cases, and in many others the young 

 leaves form an irregular, somewhat flattened mass of aborted leaves 

 with a diameter of nearly one-half of an inch or thereabouts. Many 

 of the buds affected in this manner fail to develop any leaves and 

 eventually dry up and remain upon the twigs for some months. In 

 a few instances leaves may develop successfully from closely adja- 

 cent buds. 



The very few midge larvae observed in these deformities in New 

 York led to some questioning as to the true gall producer. It was 

 therefore with more than usual interest that an examination was 

 made June '18, 1921 of a number of galls provisionally identified as 

 those of this species and just at hand from Prof. F. A. Fenton, 

 Ames, Iowa. This disclosed in the larger galls, numerous minute 

 midge larvae here and there in cavities formed by partly developed, 

 greatly aborted leaves. The larvae were upon the active green 



Fig. 3 Xylodiplosis aestivalis Kieflf., side view of 

 abdomen showing portion of the extremely long ovipositor within, 

 greatly enlarged (original). 



tissues and were sufficiently abundant in our opinion, to account 

 for the deformation observed. This applied to the larger type of 

 gall with a diameter of about three-quarters of an inch. There were 

 also on these slippery elm shoots a few blasted, partly dried galls 

 at the base of well-developed leaves. These latter had a diameter 

 of approximately one-quarter of an inch and an examination showed 

 five or more small larvae on the somewhat limited green tissues near 

 the base of the swollen bud while the apical half was mostly brown. 

 It appeared as though the infestation in the case of these smaller 

 galls had been so severe as to almost blast the development of all 

 leaves and make impossible anything but a very rudimentary growth. 



