Insect Galls. 17 



Cecidomyia^ castaneae, n. s. Fig. 18. 



An ellipsoidal, monothalamous gall found singly or in small groups 

 near the base of leaves of chestnut, Castanea dentata, projecting from 

 under side of the principal veins, occasionally from the midrib, seeming 

 to be an enlargement of the vein. It opens by a slit above, extending 

 the length of the gall, the lips tightly (dosed. The surface is smooth like 

 the surface of the leaf. The walls are succulent, from 0.6 to 1.5 mm. 

 thick at hack. Galls 6-12 mm. long, 3-6 mm. wide, 4-8 mm. deep, tap- 

 ering to union with the leaf at the ends. Light yellow-green, a few 

 tinged with red. Collected from very young trees, on short sprout from 

 base of tree, in dune, when the galls seemed well grown. 



A gall which seems to lie identical is described by C. "Houard, in Les 

 Zoocecidies des Plantes d'Europe. p. 210. This occurs on Castanea 

 vulgaris. 



Quercus. 



Cecidomyia nioeipila Osten Sacken. Oak fold-gall. 



Cecidomyia niveipila Osten Sacken, in Loew's Mon. dipt. N. A., 1862, pt. 1, p. 199-200. 



BeutenmHller, Bull. Amer. mus. nat. hist., 1892, v. 4, p. J71 ; Ins. nulls 



vicin. N. Y.. 1904, p. 31, fig. 

 Jarvis, :i~th ann. r<']>t. Ent. soc. Ontario, 1906, p. 06. 

 Irregular in size and shape, consists of a fold or cavity from the upper 

 side of the leaf. The fold is lined with white pubescence which is also 

 conspicuous on the under side. Sometimes the whole leaf is deformed, 

 sometimes only the midrib. In a large gall several larvae are found ; 

 these go into the ground to pupate. Common early on leaves of several 

 kinds of oaks, Quercus. 



Quercus, black oak group. 

 Andricus excavatus Ashmead. Excavated gall. 



Andricus excauatus Ashmead, Proe. V. S. nut. inns., 1896, v. 19, p. 121. 



Rounded, woody galls, looking as if they had been forced out of slits 

 in the twigs. Varying much in shape anci size, from 3-6 mm. in diameter. 

 Brown, monothalamous. Collected in fall, insects emerge in following 

 spring. On black oak group, Quercus. 



Quercus rubra. 

 Cecidomyia majalis Bassett. Vein gall of oak. Fig. 32. 



Cecidomyia quercus-majalis Bassett, Proe. Ent. sue. Phil., 1864, v. :i, p. 682-683. 

 Cecidomyia majalis Osten Sacken, Proe. Ent. soc, Phil., 1865, v. i. p. 340,353; Trans. Amer. 

 ent. sue. 1870, v. :>, p. 53. 



Packard, 5th rept. V. s. ent. comm., 1890, p. 207. 



Jarvis, 37th ann. rept. Ent. soc. Ontario, 1906, p. 68, pi. D, fig. 5. 



An oblong blister-like gall along the principal veins, usually on the 

 under side of the leaf. It opens by a slit on the opposite side which may 

 be opened by pulling the leaf. Green becoming brown. Sometimes veins 

 show on the gall. Thin- walled. The larva drops to the ground to trans- 



