TENT CATERPILLARS AND THEIR NESTS. 6 



If you look carefully at the surface of the limb on which 

 the procession has been marching you will see many whitish 

 silken threads. One of these threads is spun by each of the 

 caterpillars as it marches along. The thread comes from tlie 



Fig. 3. —Apple Leaves eaten by Tent Caterpillars. 



mouth in the form of a liquid, secreted by certain peculiar 

 glands, which on exposure to the air hardens into a silken 

 thread. Probably the caterpillar is guided back to its tent by 

 the thread which it spun on the outward journey. 



During cold and wet weather the caterpillars remain within 

 the shelter of the tent, sallying forth again when the spring 

 sun shows his genial face. 



About the first of June the caterpillars become full-grown, 

 as far as this part of their life is concerned. They can eat no 

 more leaves, and appear to l)e seized with a desire to wander 

 away from home. Down the tree they crawl and out into a 

 strange new world — a jungle of weeds and grass — they go, 

 seeking here and there the friendly shelter of a stone or board 

 or fence. When such shelter is found, the caterpillar halts for 



