OAK APPLES IN AUTUMN AFTER FALLING FROM THE TREES. 

 Showing holes through which the flies emerged in June. 



WHAT IS AN "OAK APPLE"? 



By HAROLD BASTIN 



With Photographs by the Author 



VEGETABLE galls are among the 

 most familiar objects of the coun- 

 tryside, yet most people ha\-e a 

 very hazy idea as to their origin and 

 signiticance. Certain kinds were — and. 

 indeed, are still — thought to be a queer 

 kind of fruit : witness the popular name 

 " oak apple." Another commonly ac- 

 cepted but erroneous theory with re- 

 gard to other galls is that they are a 

 fungoid growth. As a matter of fact, galls 

 are a part and parcel of the plant on which 

 they are found, albeit a morbid growth, 

 and are generally the outcome of irritation 

 caused by insects. Some well-kncn\n galls, 

 such as the variously coloured " nail 

 galls " on the leaves of the lime, and the 

 red, globular galls on those of the maple, 

 are due to the activity of mites^minute 

 creatures more nearly related to spiders 

 than to insects. It is. however, with an 

 insect gall that I propose to deal ; to trace. 



88 6q 



in fact, the " life history" of that familiar 

 object — the common oak apple. 



E\erybody knows the oak apple, or 

 '• King Charlie's apple." which is sported as 

 a buttonhole by countiy lads on " shig- 

 shag " day. Yet it wiU probably come 

 as a sui"prise to many to be told that these 

 pretty, fruit-hke (objects are really the 

 nurseries of certain minute four-winged 

 flies related distantly to our bees and 

 wasps. Such, however, is the fact ; and 

 to pro\e it one need only keep an oak 

 apple, which has become "ripe" and 

 brown, for a few weeks beneath an in- 

 verted tumbler. In due coui-se the tlies 

 will make their appearance, burrowing 

 through the substance oi the gaU. 



To trace the complete life cycle of the 

 oak apple gall insects. howe\-er. it will be 

 necessary for us to begin by carrying our 

 minds back to the dull, ccjIcI days f)f mid- 

 winter. For strange to say, and contrary 



