l6o THE OAK GALLS AND GALL INSECTS 



Andvicus civratus. Not common. A number of galls may 

 appear on the same catkin, but often there are only two or three 

 present. First appearance noted IMay i8th. 



(17.) Agamic Generation. VII. Andricus fecundatrix 

 (Htg.) 



Inquilines. Synergits melanopus (Htg.), S. vulgaris (Htg.) 



Gall. 



The gall grows from the bud, and somewhat resembles a 

 hop ; it is made up of numerous enlarged scales, which surround 

 the hard woody inner gall, situated at their base. This inner 

 gall is usually thrust out, and falls to the ground in late summer, 

 but this is not always the case. Colour : The true inner gall is 

 yellowish green ; the scales are green, edged with brown, when 

 young, becoming entirely brown later. 



Imago. 



Colour : Blackish. Thorax : Covered with white silky hairs with two 

 broad stripes towards the outer portion of the parapsidal furrows. These 

 stripes are smooth and glabrous. The other portions of the thorax are dull and 

 rugose. Abdomen : Black, shining, somewhat reddish at the sides. -l^^gs : 

 Usually dark, front tibice, with strong erect hairs. 



(17.) Sexual Generation. VHa. Andricus pilosus 

 (Adler.) 



These galls which occur on the male catkins, either singl}^ or 

 many together, are covered with hairs. Colour : Green at first, 

 becoming brown with age. Shape : Oval, walls thin, apex 

 prominent. 



I was unable to find this gall at Epping Forest. 



Imago. 



Black in colour, with the thorax smootli and slightly shining, and the 

 abdomen a dull black. The Atitenncs are black or brownish black, and the legs 

 are yellowish. 



Account of Generation Cycle. 

 The insects emerge from the A .fecundatrix galls in April. The 

 ova are laid in the anthers of the catkin, one egg in each anther. 

 When the male flowers develop in May, the A. pilosus galls 

 appear in variable numbers, but usually a good many on each 

 catkin. From these galls the flies emerge in June, and lay one 

 egg in a bud, many buds being pierced by each insect. Galls 



