, 'OF THE HUMAN BODY. 95 



the appearance of the former, and begin their wan- 

 derings afresh — a caterpillar leading each troop, 

 having attached to its tail other caterpillars, and 

 so on. They grow now very large, and collect 

 together, at the end of June or the beginning of 

 July, in increasing numbers. The caterpillars, 

 placing themselves side by side, or one above the 

 other, cast their skin a second time, and wander 

 again, leaving threads behind on the path of their 

 emigration. They are now excessively voracious, 

 and deposit largely the matter which is so obnox- 

 ious to men and animals. Being now more than 

 one inch in length, and very strong, they are seen 

 to make long journeys, annexing all smaller troops 

 which they meet on their way. They gather at 

 last on the trunk of a thick tree, placing them- 

 selves side by side to the extent of a man's hand, 

 and then one above another, in three or four rows, 

 after which some of the larger caterpillars are seen 

 to creep from underneath, and spin all round the 

 heap. The spinners are relieved by others at 

 regular periods, and from six to eight caterpillars 

 may be seen on the cocoon which is usually fast- 

 ened to the sunny side of the trees, rarely to the 

 stormy and northern side, at a considerable height, 



