228 



HARDWICKE'S SCIENCE-GOSSIP. 



[Oct. 1, 1866. 



GALL INSECTS. 



npHE numerous queries which from time to time 

 ■*- are submitted to us on the subject of Galls and 

 Gall Insects lead us to the conclusion that a few 

 observations thereon will prove acceptable. In our 

 first volume (p. 59) we gave a figure of the 

 common gall of the oak, which is produced by the 

 little fly known to entomologists as Cynips Kollari. 

 Hitherto the male of this insect is, as far as we are 

 aware, unknown ; but the female is commonly ob- 

 tained from the galls. Of this sex we annex a 



Fig. 215. Gall Insect {Cynips Kollari). 



figure (fig. 215), magnified about 10 diameters. Mr. 

 J. Wood recently forwarded to us for examination 

 specimens of two insects reared from these galls, 

 accompanied by the following note : — " In Septem- 

 ber, 1865, 1 collected at Sydenham, near the Palace, 

 about 150 of the galls that have of late been so 

 plentiful on the oak. I put them in a glass-topped 

 box, and in about a month from SO to 100 flies had 

 issued therefrom. These were all the ordinary 

 female insects. I took out the insects and the 

 empty galls, and left the remainder until about the 



Fig. 216. Gall Insect {Cynips sp.) 



middle of June of the present year, when I found a 

 few more insects like those which had come out 

 before, and also about a dozen others such as I had 

 not seen before, which I at first took to be the 

 males of the same species. They are smaller, 

 dark brown, and regular little dandies." We 



submitted these latter insects to the most com- 

 petent judge with whom we were in communication, 

 and who has devoted considerable attention to the 

 study of their allies. This gentleman states that he 

 regrets his inability to name the Cynips (fig. 216), 

 but that both the specimens are females, and there 

 are specimens of it in the British Museum. It is 

 singular, he adds, that this species has not been 

 observed before, as large numbers of the Devon- 

 shire galls have been frequently kept for the 

 purpose of rearing the insects from them. At 

 present, therefore, we can give no further informa- 

 tion about them. Dr. Xirchner states that Synergus 

 facialis, Hart., is a parasite of Cynips Kollari., 

 which, however, is very different from the insect 

 here figured. 



a 



Fig. 217. Oak-leaf galls, «, upper portion, with "Oak 

 spangles;" b, lower portion, with " button galls." 



Two kinds of discoid galls are extremely common 

 on the under surface of oak-leaves, presenting an 

 appearance so singular that persons are continually 

 being puzzled with them, and appealing to us for 

 information. The figure above will perhaps 

 help to clear up the difficulty. One portion 

 (fig. 217 a) represents the top of an oak-leaf 

 bearing "oak spangles," and the lower portion 



