10 



branches to the crotch and transform unprotected in the hollow of the 

 crotch. 



The larva is elongate, reaching when full grown (fig. 3, e) half an 

 inch in length. When first hatched it is nearly black; as it increases 

 in size it becomes, with each shedding of the skin, more distinctly 

 marked with yellow, and when mature the yellow predominates, 

 occurring as a broad dorsal stripe and two lateral stripes. 



The difference between the early work of the beetles and the later 

 work of the Iarva3 is recognized at a glance. The beetles eat entirely 

 through the leaves and make complete, irregular holes, while the larvae 

 simply eat the parenchyma from below, skeletonizing the leaf. 



The time occupied in egg laying is long, and it thus happens that at 

 the time when full-grown larvae, and even pupae, are to be found there 

 are also upon the leaves freshly laid eggs. 



In Washington there are invariably two generations annually, the 

 beetles developed from the eggs laid by the overwintered beetles them- 

 selves laying their eggs in July. The adults issuing from these eggs 

 make their appearance in August. Farther north, at New Brunswick, 

 N. J., and in the Connecticut cities, it may be said that there is nor- 

 mally a complete first generation and an incomplete second generation. 



The proper food of the larvae is the rather young and tender leaves. 

 If the work of the first generation has not been complete, and the trees 

 have not been so nearly defoliated as to necessitate the sending out of 

 fresh leaves, or if a period of drought ensues after defoliation and pre- 

 vents the putting out of a second crop of leaves, the beetles of the first 

 generation do not lay eggs, but after flying about for a time seek winter 

 quarters. This may occur as early as the middle of July. Where, 

 however, defoliation has been complete and has been followed by a 

 period of sufficient moisture to enable a tree to put out a fresh crop of 

 leaves, the beetles of the first generation will lay their eggs and a sec- 

 ond generation of larvae will develop upon this comparatively tender 

 foliage. Where similar conditions prevail in Washington and its 

 vicinity, a third generation of larvae may develop, though small in 

 numbers, but the writer is convinced that even in Washington late- 

 developing beetles of the first generation may hibernate. 



Remedies. The only thoroughly satisfactory safeguard against this 

 insect consists in spraying the trees with an arsenical solution. The 

 only other remedy which is worthy of mention is the destruction of the 

 larvae at the surface of the ground before or after they transform to 

 pupae. The latter remedy, however, is not complete, and even where 

 it is carefully carried out for every tree in a city it will do no more than 

 reduce the numbers of the insects by perhaps two- thirds. 



Ten years ago a proposal to spray the enormous elms which are to 

 be found in many Northern towns would have been received with 

 ridicule, but of recent years the practicability of the plan has so fre- 

 quently been demonstrated that there is no hesitancy in commending 





