172 THE OAK GALLS AND GALL INSECTS 



When they occur in great numbers on a single plant, as is 

 often the case with young stock, they are exceedingly injurious. 

 I have seen many young trees covered with the galls, completely 

 stunted and practically useless. 



The galls are of little or no use for ink making purposes, 

 because as Cameron remarks, they contain only seventeen per 

 cent, of tannic acid as against fifty per cent, in Aleppo and other 

 :galls. 



The presence of tannic acid in the gall acts perhaps as a 

 protection for the enclosed larva, though birds often peck the 

 galls open to get at the grub, in spite of their bitter properties. 



The galls are very liable to parasitic infestation and harbour 

 inquilines and commensals ; the presence of these intruders can 

 often be told by various wart-like excrescences wdiich appear on 

 the outer surface of the galls. 



(27). Agamic. I. Cynips kollari (Htg.) 



Inquilines. Synevgus pallicoynis, S. melanopiis (Htg.) and S. 

 ninliavdi (Mayr). 



Gall. 



Appears from terminal and axillary buds. Round in shape, 

 varying in size up to 3 m m. Green to brownish red when 

 young often at this time marked with darker spots, the apex is 

 usually drawn out and slightly bent. As they become older and 

 ^row larger they assume a golden yellow colour or remain quite 

 green ; in both cases they turn brown subsequently, at 

 maturity. 



Single celled unless parasitised. 



Very often tw^o galls may be found joined in one, in which 

 case there is usually one larval cell containing a single larva. 

 The gall substance is much harder immediately around the 

 larval chamber than elsewhere, w^ith the exception of the outer 

 epidermal tissue of the gall. 

 Imago. 



Colour: Reddish yellow, which varies shghtly in intensity. Antetmae'. 

 13-jointed, basal joint pale, third joint longer than the others. Thoiax : 

 Pubescent, parapsidal furrows complete, scutellum completely covers the 

 metanotum which, like the median segment, is very dark. Abdomen : Smooth, 

 shining, more or less black above, partially covered with a silky pubescense. 

 Ovipositor : Long and spiral. Lfos : Yellow, paler than the boiy, fore librae 

 •fiinged with hairs. /F/z/^-.f : Long, hyaline, and slightly hairy. 



