128 Bulletin 233. 



one can often pick 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 .3 mm. 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 determined 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. Alany larvae had begun 

 their mines by Alay i8th in 1905. I have found forty-three unhatched 

 eggs and at least twenty-five mines just begun in a single large elm leaf 

 (Fig. 26).''' I have not found any characters wdiich will readily separate 

 the nearly-grown larva of this elm sawfly from those of the alder sawfly 

 discussed on page 134. 



On ]\Iay 27th, 1904, I found on the Scotch elms on the Cornell 

 Campus many of the sawflies, many recently laid eggs and many larval 

 mines just begun in the leaves. By June ist, some of the larvae were 

 nearly grown, and on July 4th practically all had left the leaves, no stage 



* Tiie following interesting details of the larval stages are quoted from Healy's 

 account (The Entomologist, IV, 298). " The larva has a white bod}-, and is in 

 possession of 22 legs, the first six of which are annulated with dark brown; the 

 claws are also dark brown ; the head is tinged with pale brown of a darker tone 

 at the sides, mouth reddish brown, eyespots brown, and its dorsal vessel is dull 

 green ; the under side of the second segment has a dark, oblong-shaped plate down 

 its center, and on either side of tliis there are two brownish dots ; on running our 

 eyes down the remaining segments we observe that, excepting the anal segment, all 

 are furnished with a small black-colored dot ; the fifth segment has no organs of 

 progression. At the first moult the decorative markings of the larva are all thrown 

 off, and if at that time we closely inspect the under surface of the body we perceive 

 a slight remnant or pigmentary deposit on the segments situated as the exact spots 

 where the black ventral dots were located previous to the moult ; these dusky marks, 

 however, soon fade away, and leave the segments entirely spotless; the head and 

 eyes slowly resume their original color, and the six thoracic legs regain their annula- 

 tions. A\'hen full-fed it peases to feed, and lies in its mine in a state of repose, and 

 throws off its skin for the last time; by and by a faint yellowish tinge spreads itself 

 over the body of the larva. At the appointed time the larva liberates itself from its 

 mine by biting a hole in it. At the last moult the brown-colored bands on its six 

 anterior organs of locomotion are thrown off entirely. Escaping from its mined 

 abode, the little creature drops to the ground, and now, every time it is touched, it 

 instantly partially curls its body up, remaining in that position only for a moment 

 or two." 



