Two New Shade-Tree Pests. 



125 



and unsightly appearance about July ist, but in two months have nearly 

 recovered their beauty. The insect is thus capable of defoliating and 

 checking the growth of young trees, and of rendering large trees un- 

 sightly for a time in midsummer. 



Its life-history and habits. — In 1869, Healy recorded (The Ento- 

 mologist, Vol. I\', p. 297) many interesting details of the life of this 

 sawfly, and the European literature contains but few additional notes. 



After July 15th, I have not found the insect on the trees again until 

 the next ]\Iay. In July the larvre which mined the leaves go into the 

 ground, beneath the trees for a short distance, an inch or less. There they 



Fig. 24. — Larvcc of elm sazcfly Icaf-iiiiiicr. iinich Fig. 25. — Three eggs of elm SincHy 



enlarged. 'J'liis figure also serz'es for the leaf-miner stuck in leaf. Much 



alder saz^ily larz'ce. as the tzco species are enlarged, 

 much alike in this stage. 



make small, thin, brown, elongate, papery cocoons in which they remain 

 as larva." for nearly ten months, or until late in April. About May 1st, 

 they transform through tender pale-yellowish pup?e, apparently in about 

 a week, into the black adults or sawflies which begin to emerge about 

 the middle of May. Many had emerged by May loth, in 1905. 



On May 27th, 1904, I found hundreds of the flics on the elm leaves. 

 About 1:30 P. M. only a few of the flies were seen, but at 3:00 p. m. 

 when it was more sunny, they were very numerous. The flies are almost 

 invariably on the upper surfaces of the leaves and are so " tame " that 



