Rk- report of the state entomologist 1918 199 



This insect is possibly Cecidomyia erubescens 0. S.' 

 though as no stage of the insect was described, it is impossible to 

 be certain without exhaustive rearings from a variety of marginal 

 oak leaf rolls. The species was discovered by W. V. Tower in July 

 ,1905, working on the leaves of black oak. His observations on its 

 life history were continued by H. M. Russell and subsequently 

 C. W. Hooker completed the account. The marginal rolls (pi. 13, 

 fig. i) produced by this insect were very abundant on a black oak 

 (Quercus coccinae, var. tinctoria) growing near the 

 president's house on the grounds of the Massachusetts Agricultural 

 College at Amherst, Mass. The infested tree was in a small clump 

 of red oaks, none of which became infested, apparently indicating 

 that this species occurs only on the black oak, particularly as the 

 larvae were numerous upon the leaves and adults occurred in swarms 

 under its branches. Every leaf was infested by from one to over 

 one hundred larvae up to certainly within 10 feet of the top, though 

 they were not so numerous on the upper branches as on the lower 

 limbs. Our own observations show that certain Cecidomyiidae at 

 least, display a marked preference for the foliage of the lower limbs. 



Male. Length i mm. Antennae one-fourth longer than the body, 

 thickly haired, dark brown; fourteen segments, the fifth with stemS 

 three-fourths and two times their diameters, respectively; terminaJ 

 segment, distal enlargement slightly produced, apically an irregular 

 conical projection. Palpi; the first segment rather long, stout 

 expanded distally, the second a little longer, more slender, the third 

 one-half longer than the second, more slender, the fourth three- 

 fourths longer than the third, somewhat dilated. Mesonotum dull 

 black. Scutellum deep red, postscutellum yellowish. Abdomen 

 deep red, the basal segments fuscous. Wings hyaline, costa reddish 

 brown; halteres pale yellowish. Coxae, femora and tibiae mostly 

 fuscous yellowish, the tarsi a little darker; claws long, slender, slightly 

 curved, the pulvilli a little shorter than the claws. Gemtalia; 

 dorsal plate short, broad, deeply and triangularly incised, the lobes 

 diverging, narrowly and irregularly rounded; ventral plate long, 

 broad, the sides somewhat emarginate, broadly and roundly emar- 

 ginate, the lobes short, obtuse; style stout, long and tapenng, nar- 

 rowly rounded. .11 .li_ -f +1. 



Female. Length 1.5 mm. Antennae one-half the length ot the 

 body, sparsely haired, reddish brown; fourteen subsessile segments 

 the fifth with a length two and one-half times its diameter; terminal 

 segment slightly produced, with a length four tmies its diameter 

 and a short, stout process apically. Tarsi ; first segment subquadrate, 

 the second with a length twice its diameter, expanded distally, the 

 third a little longer, narrowly oval, the fourth one-half longer than 

 the third, slightly dilated. Ovipositor one-third the length of the 

 abdomen, the terminal lobes with a length twice the width, narrowly 

 oval. Otherwise nearly as in the male. Cecid. 1339. 



