OAK-APPLES ' : galls caused by the presence of the grubs of the hymenopterous insect Teras terminalis, 

 and (inset) ' PINE-APPLE GALL' on spruce fir, caused by tne presence of the 

 Aphid insect, Adelges abietis. (Photos by H. Irving and A. W. Dennis.) 



(Left) 'ARTICHOKE GALLS' caused by the 



presence of the grubs of Aphilothrix fecundatrix, 



(Right) 'MARBLE GALL' caused by the 



presence of the grubs of Cynips kollari. 



Both insects are hymenopterous, and deposit their 



ep-prs in oak twi^s. (Photo by H. Irving.) 



'WITCHES' BROOM' ON BIRCH 



A ' gall ' caused by the presence of the mite, 



Eriophyes rudis. (Photo by H. Irving.) 



