LIFE HISTORY OF THE CATERPILLAR 



129 



leaves, but remain in closely associated colonies, as repre- 

 sented in Fig. 44. As they increase in size they eat more and 

 more of the leaf substance; when half grown they devour all 

 but the midrib and the side veins, but when they get larger 

 only the midribs arc left, as may be seen in Fig. 43. 



ft 



Fig. 45. Denuded Elm twig showing carpet web. 



The carpet-web "that they form becomes more conspicuous 

 as the caterpillars develop, and often binds the ends of neigh- 

 boring twigs together, especially in those places to which the 

 caterpillars retire for rest after feeding. Examples of such 

 webbing of the denuded surface are shown in Figs. 45 and 50. 



