of certain species of WiHoto. — Part 2nd. 257 



No. 21. Gall S. desmodioides. n. Bp. — On S. humilis. A smooth, flattish, 

 fleshy, BeaBile,yellowi8h-green, monothalamoua gall of a semicircular outline, the 

 chord of the semicircle adjoining the midrib of a leaf; its general shape like the 

 l of a Deamodium, or like the so-called "quarter" of an orange, the thin in- 

 side edge of the "quarter" closely hugging the midrib of the leaf, and the ro- 

 bust outer surface not biangulated but rounded off. No rosy cheek. The vol- 

 ume of the gall is generally about equally divided between the upper and lower 

 sides of the leaf, but sometimes the lower portion is rather the larger. Usually 

 there is but a single gall on a single leaf, but occasionally there are two of them 

 either on the same side or on opposite sides of the midrib. One leaf was noticed 

 with as many as three of these galls upon it. Length .23 — .50 inch; 131 speci- 

 mens. The above is the appearance of the mature gall July 30; but on May 17 

 it is already nearly full-sized, and then many of them have a rosy cheek like 

 the normal S.pomum. Abundant and not local. Distinct from S. pomum by its 

 very different shape, and by its never having any rosy cheek when mature, and 

 by the very distinct species of willow on which it occurs. 



Larva. Three or four larvae examined July 30 did not differ apparently from 

 those of -V. 8. pomum examined on the same day. When the larva quits feeding 

 on the gall, there remains nothing of it but a shell as thin as paper. All the 

 imagoa bred bymepupized inside the gall, but there was no earth in the breed- 

 ing vase for them to retire into, and April 2 I found several dead and dried up 

 larvae at the bottom. 

 Pupa unknown. 



Imago. Nematus s. desmodioides. n. sp.— 9 Shining greenish-white. Head 

 with tin 1 eyea, a quadrate spot enclosing the ocelli, and nearly reaching the an- 

 tennae, but always separated from the eyes by an orbit which is almost always 

 pretty wide, and also the tips of the mandibles, all black. Olypeus emarginate 

 in a circular arc of about 90°. Labrum rounded at tip. Occiput always with a 

 more or less dark black cloud on its upper disk confluent with the ocellar quad- . 

 rate spot, so as to conceal generally the capillary black lines so conspicuous in 

 X. s. pomum. Antennae A as long as the body, joints 3 — 5 subequal, 6 — 9 slowly 

 shorter and shorter, 9 sometimes as long as S, the scape black, the flagellum 

 brown-bla'ck. Thorax, including the basal plates, black, with the tegulfe, a pair 

 of obscure spots transversely arranged on the scutel and sometimes contiguous, 

 the entire collare, except generally a lateral black spot on its lower angle, and 

 a large obscurely defined triangular spot of variable size on the upper part of the 

 meso thoracic pleura, all greenish-white. Rarely (2 gout of 8 9 ) the mesonotum 

 is dull rufous, with a broad bla.-k vitta reaching from the collare to the scutel 

 and the extreme tip of the scutel black, as in many S. pomum J • Cenchri 

 whitish. Abdomen, except generally the extreme tip. black above, the lateral 

 plates black towards the base of the abdomen, greenish-white towards its tip. 

 Basal membrane whitish. Cerci usually greenish-white, rarely tipped with 

 dusky. Ovipositor greenish-white ; its sheaths black. Venter always immacu- 

 late, tinged more or less with honey-yellow. Legs greenish-white, the hind 

 legs aometimea tinged with honey-yellow; tarsal tips, especially in the hind 

 legs, and generally the extreme tips of the hind tibiae, obfuscated. Wings hya- 

 line; veins black; costa and stigma pale dusky, the basal J of the stigma tinged 

 with greenish-white. The 3rd submarginal cell varying from i longer than 

 wide to a little shorter than wide. In one wing of one 9 ( anu also of one % ) 

 it is entirely absent. Length 9 .15— .19 inch; front wing 9 .17— .20 inch. 



