Galls 



24. Woody plants show curving of shoots, e.g. in 

 apples, currants, and gooseberries, usually accom- 

 panied by a discoloration of the bark : early aphis 

 attack. 



25. Woody plants show stunted growth and 

 general unthriftiness : they should be closely 

 examined for scale insects on the bark. 



26. Palms, ferns, and aspidistras, etc., show 

 discolored spots on the leaves or leaf-stalks : search 

 should be made near the " crown " and mid-ribs for 

 scale insects. 



III. Galls, that is. Enlarged Growths, 

 Produced 



27. The attacks of insects and other animals of 

 many different types result in enlarged growths 

 which take on extraordinarily different forms accord- 

 ing to the kind of insect and the kind of plant. The 

 galls upon the oak illustrate this in a remarkable 



, way, and perhaps no more remarkable story is to 

 be found among the annals of insect life than that 

 of the gaU insects of the oak. This is not the place 

 to do more than refer to the fact that oak-apples, 

 artichoke galls, marble gaUs, spangle gaUs, currant 

 galls, and many others, all of which may be found^ 

 in practically any oak coppice, are the result of 

 insects of various kinds laying eggs in the oak, the 

 grubs which hatch from them being found in the 

 galls and feeding upon their tissues. 



114 



