In the Midwinter Forest 19 



tales used to be told about them. In Germany 

 they are called " thunder besoms," while in Eng- 

 land and in our own country they are known as 

 "witch's brooms" (Fig. 8). 



The witch who makes them has been caught in 

 the act. She is a tiny fly, taught by nature to 

 pierce the twig, and to put her eggs into the pith. 

 The warmth of spring hatches these into gnats 

 — a hungry host. They live and feast inside the 

 branch, and distort and deform its growth so that 

 it puts forth these crowded clusters of twigs. 

 Every broom is a fly nursery. 



On oak branches we may see little smooth 

 knobs, the color of the dead leaves. These are 

 one kind of oak gall. In England they are still 

 known as " oak apples," for the name apple used 

 to be bestowed upon any fruit or anything that 

 looked like fruit. 



The oak apple, so called, is an ill-treated leaf, 

 pierced by a mother gall-fly. She put an egg into 

 its middle vein, and thus turned it into a nursery 

 for her offspring. By late summer such a nursery 

 has become a shell filled with a brown spongy 

 substance. In the center of this is a hard kernel 

 about as big as a pea, and inside all is a white 

 grub, one of the insect foes of the oak. 



The oak apple falls to the ground in some win- 

 ter gale, and in spring the grub, now changed 

 into a gall-fly, eats its way out. On the oaks 

 there are other galls that will not fall until the 



