ORDER HYMENOPTERA 219 



of the Entomological Society of London, 1877, p. xvii) that 

 in an infestation of maples near Brussels "the flattened case 

 formed by the larvae when full-fed made quite a pattering 

 noise as they fell from the trees." 



FENUSINAE 



All the species of the Fenusinae, whose habits are known, 

 have leaf -mining larvae. In America as well as in Europe 

 there are several examples. Two or more of our species in 

 this group have been introduced from Europe but some are 

 probably native. Their eggs are inserted in the leaf. They 

 mine in blotches. In the sixth instar they leave the leaves 

 and enter the ground where at least most of the species 

 make a slight cocoon of silk or salivary secretion and earth. 



The elm-leaf sawfly, Kaliofenusa ulmi has been imported 

 from Europe and in America it particularly attacks its chief 

 European host plants, the English and Scotch elms. From 

 these it sometimes spreads to the American elm. Its in- 

 festations of these European shade trees is often very severe. 

 It was exceedingly common in Albany, New York, and 

 vicinity from at least 1895-1900. For several years there 

 was a very severe infestation on English and Scotch elms at 

 Ithaca, New York. As high as 90 per cent of the leaves were 

 sometimes infested; and as there were often five or even 

 more mines in a leaf, and as almost every vestige of paren- 

 chyma was eaten out of the mined areas, the growth of the 

 trees was very seriously affected. 



At Ithaca the adults emerge early in May. In 1915 

 they were abundant on the trees by May 12th but some were 

 still crawling up through the earth and a few were found 

 just emerging from some cocoons obtained by sifting soil 

 from below the trees. In cold or windy weather they will 

 be found hidden away in the partly unfolded leaves at the 

 tips of the branches but on warm sunshiny days they are 

 active, flying about the trees and ovipositing. The eggs 



