in HERMIT HOMES 91 



her ovipositor and thrusts it instantaneously into 

 the leaf or other object, making a puncture, subse- 

 quently widened by -boring. Into the hole she drops 

 one or more eggs. To conclude, she spreads a slight 

 quantity of secretion over the wound, so irritating to 

 the plant's tissues as to alter their nature, and de- 

 velop, but how we know not, the irregular swelling 

 of the cellular structures that we term a gall. Midst 

 the fleshy chamber thus constructed the eggs are 

 hatched, and the larvae live on its interior. The 

 insects remain within the galls until they have under- 

 gone all their changes, and emerge, eating their way 

 out into the open air, upon their attainment to the 

 perfect form. Others escape as larvae, and burrow 

 into the earth for their later metamorphoses. 



Forty-two or more kinds of galls occur on oaks in 

 Great Britain alone, but the damage done to the trees 

 seems almost immaterial. There are the familiar 

 oak-apples, arranged usually several together in small 

 clusters on the twigs and branches, irregular in 

 shape, and sometimes of enormous size, the work 

 of Cynips terminalis. These contain an aggre- 

 gation of cellules, twelve to fifteen or more, the 

 hermit habitations of solitary larvae. From the 

 separate cells a fibre, as it were, runs towards the 

 base of the gall. Probably these fibres are the 

 nervures of leaves which would have sprung from 

 the bud in which the eggs were laid, had not the 

 irritating fluid caused them to develop in a new 

 manner. The well-known small oak-apples found in 

 profusion on oak leaves are due to the puncture of 

 Cynips quercus folii. Well they deserve their popular 



