Insect Study 



357 



THE LEAF-ROLLERS 



Teacher's Story 



^ we look closely at sumac leaves before they are 

 aflame from autumn's torch, we find many of the 

 leaflets rolled into little cornucopias fastened with 

 silk. The silk is not in a web, like that of the 

 spider, but the strands are twisted together, 

 hundreds of threads combined in one strong 

 cable, and these are fastened from roll to leaf, 

 like tent ropes. If we look at the young bass- 

 woods, we find perhaps many of their leaves cut 

 across, and the flap made into a roll and likewise 

 fastened with silken ropes. The witch-hazel, 

 which is a veritable insect tenement, also shows 

 these rolls. In fact, we may find them upon the 

 leaves of almost any species of tree or shrub, and 

 each of these rolls has its own special maker or indweller. Each species 

 of insect, which rolls the leaves, is limited to the species of plant on which 

 it is found ; and one of these caterpillars would sooner starve than take a 

 mouthful from a leaf of any other plant. Some people think that insects 

 will eat anything that comes 

 in their way; but of all 

 created animals, insects are 

 the most fastidious as to their 

 food. 



Some species of leaf -rollers 

 unite several leaflets together, 

 while others use a single leaf. 

 In the case of the sumac leaf- 

 roller, it begins in a single leaf; 

 but in its later stages, it 

 fastens together two or three 

 of the terminal leaflets in order 

 to gain more pasturage. The 

 little silken tent ropes which 

 hold the folded leaves are well 

 worth study with a lens. 

 They are made of hundreds of 

 threads of the finest silk, 

 woven from a gland opening 

 near the lower lip of the cater- 

 pillar. The rope is always 

 larger where it is attached to 

 the leaf than at the center, 

 because the caterpillar criss- 

 crosses the threads in order to 

 make the attachment to the 

 leaf larger and firmer. Unroll a tent carefully, and you may see the 

 fastenings used in an earlier stage, and may even find the first turned-down 

 edge of the leaf. However, the center of a leaf roller's habitation is 

 usually very much eaten, for the whole reason for making its little house 



Leaf-rollers in sumac, with diagram showing the 

 fastening of the silk-stay-ropes. 



