DESCRIPTIONS OF OAK-GALLS. 



161 



Fiff. 67. — N. osTREUs. 



Boh., all of which appeared in the spring of the second year. 

 — E. A. Fitch. 



67. Neuroteriis ostreus, Hart. — 

 This small gall appears in July at 

 the side of the midrib on the under 

 side of the leaves of Quercus sessili- 

 Jlora, Q. pedunculata, and Q. pu- ( 

 bescens. At first it is enclosed in a 

 membranous covering, which later 

 on splits into two similar flap-like 

 parts and dries up, whilst the gall 

 increases in size, and generally 

 reaches an oviform, rarely spherical, shape, with a longitudinal 

 diameter of 3*8 millimetres. It is smooth, hairless, at first green 

 or yellow, but subsequejitly becomes, especially when exposed 

 to the sun, covered witli beautiful little red or violet circular 

 patches or spots, which are either placed in diagonal rows, 

 crowded together, or tolerably evenly scattered ; it is mode- 

 rately hard, and contains a relatively large larva-cell without 

 an inner gall. The galls fall in August and September, and 

 leave the envelopes on the leaves. Dr. Giraud obtained the 

 producers in autumn, after he had collected the fallen galls. 

 — G. L. Mayr. 



The galls of this species have occurred in almost every 

 locality in England and Scotland where looked for. I have 

 found them to vary greatly in size, shape, and colour ; but 

 this is partly owing to the influence of parasitism. However, 

 I think it is doubtful whether we have not more than one 

 closely-allied species yet unrecognised. Giraud, who was 

 the first to describe the insect, possessed a dozen specin)ens, 

 " some obtained towards the middle of October from galls 

 collected in great quantity towards the end of September, 

 and others captured on the 28th of October upon the buds of 

 oak, where iney were occupied in laying their eggs." With 

 Miss E. A. Ormerod a specimen emerged on September 7th ; 

 and I have bred the gall-makers in December. Mr. Miiller, 

 besides breeding specimens in the second week of October, 

 also obtained the Neuroierua in May and June from hyber- 

 nated galls (Ent. Mo. Mag vii. 209). This last fact is opposed 

 to Giraud's autumn egg-laying ; but it is possible that Miiller's 

 summer-bred specimens appertained to Syiiexjus, as Dr. Mayr 



