Two New Shade-Tree Pests. 



53 



brown, elongate, papery cocoons in which they remain as larvee for nearly ten 

 months, or until late in April. About May ist, they transform through tender 

 pale-yellowish pupse, 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 flies on the elm leaves. 

 About 1:30 p. M. only 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 one can often pick 



Fig. 24. — Larv(e of elm sawfly leaf-miner, much Fig. 25. — Three eggs of elm sawfly 



enlari;ed. This figure also serves for the alder leaf-miner stuck in leaf. Much 



sawfly larva as the two species are much alike in enlarged, 

 this stage. 



them up with the fingers and easily collect them in cyanide bottles. None 

 have been seen mating and I have found no males. When disturbed, they 

 fly but a short distance, so that the insect spreads slowly. 



The round, thin-shelled, milky-whitish eggs about .3mm. in diameter are 

 stuck into the leaves, often near the midrib, through slits cut with the female's 

 saw-like ovipositor (Fig. 27). The location of the eggs is more readily deter- 

 mined from the under side of the leaf where pimple-like elevations of the 

 epidermis appear in two or three days over the eggs, as shown in Fig. 25. But 

 the eggs are stuck into the leaves from the upper side, as I observed repeatedly, 

 the ovipositor evidently reaching nearly to the lower epidermis. It requires 

 from forty to sixty seconds to lay an egg. The eggs hatch in about a week. 

 Many larvae had begun their mines by May i8th in 1905. I have found forty- 



