146 



FOREST ENTOMOLOGY. 



sit closely on the leaf, and they give rise to deep windings on the 

 edge of the leaf, which is said to be caused through the gall originat- 

 ing on a rudimentary leaf within the hud. 



4. Neuroterus NUMiSMATis, 01. (Button Gall). 



This gall (fig. 139) is very common in the autumn. It is very 

 pretty, circular in shape, about 2 mm. in diameter, hard, with a shal- 

 low depression in the centre. I have not hatched the flies nor found 

 the alternate form — viz., 4a Spathegaster vesicatrix (Schltdl.), — 

 which are found on the under side of the leaf, and are rather incon- 

 spicuous, as they are embedded in 

 the substance of the leaf.i 



There is another species in the 

 group of which Adler was not 

 quite sure about fixing the genera- 

 tion cycle. This is the gall of 



5. jSTeuroterus ostreus (Htg.) 



This is a very small gall, not 

 larger than a leaden pellet, and al- 

 ways formed on the midrib of the 

 leaves, and very slightly attached. 

 It is very prettily marked, and the 

 pale - yellowish colour brightened 

 ,,.1. li,. liui.ii.Miuiii.s. i3y retj spots is suggestive of the 



miniature egg of some bird. It is common in 

 September and October. From the early matured galls flies hatch 

 out in October, but those not maturing until October do not yield 

 gall-flies until the following spring. I kept some in confinement, and 

 they hatched out on April 25, 1895. The fly is about 2 to 2| mm. 

 in length, of a black shining colour, with dull thorax, legs yellowish 

 in slender portion and dark at top next to body ; antennae longish and 

 slender, wings comparatively long. 



As Dr Adler is not quite certain about the generation cycle of this 

 species, it may be best to quote his own words — viz. : " I strongly 

 suspect that the sexual generation belonging to !N"euroterus ostreus 

 is to be sought for in Spathegaster aprilinus," and this conjecture 

 has since proved to be correct. 



^ I have since received this species from Mr E. T. Comiolcl. 



Fig. l39.-Gansof:s 



markings of a 



