274 0^^^ GALLS AND GALL INSFXTS 



Parasites attackin<{ gall-makinL^ insects belonj2;inpj to the 

 Cynipina are chietiy members of the family Chalcididae. These 

 are small blue or green-metallic coloured Hymenoptera preying 

 upon both larvae and pupae, the same species being often found 

 in different galls. 



Ichneumonid and Braconid forms, parasitic on the Cynipid 

 oak gall-makers, are not numerous. 



Parasites often prey upon the larvae of Inquilines. Certain 

 Cynipidae are parasites upon other insects, such as Aphidae, and 

 are sometimes found in the galls of members of their own 

 family. 



Parasites reproduce themselves sexually. Agamic forms, 

 are, however, found among Inquilines, the genus Cevoptres 

 furnishing examples of both kinds. 



Protection against Parasites. 

 Various devices for the protection of the larvae against 

 these intruders are consequent!} necessary, and it is on this 

 account to a large extent that galls present such a variety of 

 form and structure. Hairs may be produced in abundance on a 

 gall, as in the case of Andricns vamuli, where it is covered with a 

 dense white matted growth, or a few stiff hairs may be present 

 [Ncurotcviis tricolor). In Andricus fectindatrix, the gall is com- 

 pletely imbedded in an abnormal growth of scale leaves, giving 

 it the appearance of a hop. A covering consisting of the phloem 

 or bast cells of the peripheral layer protects Andricns covticis 

 galls. In the case oi Andricns sieboldii, the gall secretes a sweet 

 sticky substance, of which ants are very fond, and these latter 

 insects often protect the galls with a hood of earth. A hard woody 

 growth near the centre of the gall serves as an extra means of pro- 

 tection to the larva in the case of Cynips kollari . In other cases 

 the larva may be enclosed in a separate cocoon within the gall 

 [Andricns cnrvatov and A. iiiflator). The substance of the gall may 

 be very bitter and obnoxious to birds which peck at it to get at the 

 larva within [Cynips kollari). Other galls are highly coloured as a 

 warning to birds [Biorhiza terniinalis). The most interesting 

 form of protection is that of -'Protective Resemblance" where 

 galls take the likeness of buds so accurately that even when 

 specially searching for the galls one is liable to pass them 

 ov:r without notice [Andricns albopnnctata). Parasites often 

 distort galls either by stunting them or causing them to swell.. I 



