DESCRIPTIONS OF OAK-GALLS. 69 



others, contains all agamous species. Hartig bred N. para- 

 siticus from the gall of A. globuli, and N. inquilinus from 

 that of 2). scutellaris ; but these differ somewhat in structure, 

 as well as habits, from the typical Neuroteri, and have very 

 properly been transferred to a separate genus (it was partly 

 done by Hartig himself), leaving Neuroterus with only 

 gall-producing species. 'V. numismalis, the species more 

 especially under consideration, is the maker of the beautiful 

 "silky-button" galls, so abundant everywhere under oak- 

 leaves in September and October; it is generally found in 

 company with the following species, often interspersed with 

 it, on the same leaf, but the gall-maker appears to attain the 

 penultimate or pupa state somewhat earlier than its congeners. 

 I can speak to this of my own observation, but prefer lo give 

 Schlechtendal's dates, which are as follows: — "Galls collected 

 on the 3rd November, when opened on the 11th already 

 contained pupae with coloured eyes; on the 13th December 

 these pupae were coloured throughout, and the flies emerged 

 on the 15th." This occurred with galls kept in-doors. And 

 he further says the 14th February was the first appearance 

 made by a Neuroterus of its own accord. These galls are 

 generally distributed in Britain, having been recorded as far 

 north as the Cheviots, Perth, and Aberdeen. Only one 

 species of Synergiis is known to inhabit these galls, viz. 

 S. Tscheki (Mayr), which appears in March. Specimens of 

 this inquiline were no doubt taken for the true gall-maker by 

 Walker, who says: — "Last year (1845) I reared from these 

 galls two hundred and fifteen flies, of which there were fifty- 

 seven males and one hundred and fifty-eight females." 

 (Zool. iv. 1457.) The list of ChalcidicB bred at the same time, 

 and given by Walker, is as follows: — "June (second year): 

 Callimome jnutabilis, one male ; Platymesopus tibialis, one 

 male. July : Eurytoma curia, one male and one female; E. 

 ^Ihiops (Boheman), one female; Callimome mutabilis, eight 

 males and twelve females; C. inconstaus, one female; C. 

 geranii, one female ; Pteromalus domesiicus, one female. 

 August: Eurytoma carta, one female; Callimome mutabilis, 

 one female ; Eupelmus urozonus, one female." I have bred 

 Pleurolropis sosarmus in May. Dr. Mayr does not seem to 

 have been so well acquainted with this gall, as from its great 

 abundance and general distribution in this country we should 



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