ALTERATION OF FORM BY GALL-PRODUCING INSECTS. 



541 



several Cynipedes, e.g. Aphilotrix Sieboldi (see fig. 364 ^) lay their eggs in the green 

 cortex of the young twigs. Solid galls are very rare on roots, but they do occur 



Fig. 364.— Various Oak-galls. 



1 Solid galls on the cortex produced by Aphilothrix Sieboldi. 2 Bud-gall from a foliage-bud produced by Cynips Hartigii. 

 8 Solid galls on an Oak twig produced by Cynips Kollari. 4 One of these galls cut in half, s Bud-galls from foliage-buds 

 produced by Cynips lucida. ^ One of these galls cut in half. ? Leafy bud-galls produced by Aphilothrix gemmcB. 

 8 Bud-galls from foHage-buds produced by Cynips polycera. 9 Longitudinal section through one of these galls. 10 Gall 

 on the pericarp of Quercus pubescens produced by Cynips caput-medusce. n-i* Spangle galls on a leaf of the Turkey Oak 

 (Quercus Cerris); i^ produced by Neuroterus lanuginosus; 12 by Neuroterus nuTnismatis ; i^by Neuroterus /uTnipennis ; 

 1* by Spathegaster tricolor. 



in this situation in the oak, being produced by the gall- wasps Aphilothrix radicis 

 and Biorhiza aptera. 



