THE SNOW-WHITE LINDEN MOTH 59 



they want become a little over two inches in length, but when they are 

 crowded and the food supply limited they are often less than two inches 

 long. During 'their growth the larvae molt five times or even six times. 

 Graef and Weibe record only three molts. 



The caterpillars of this moth have the three pairs of true legs attached 

 to the thorax, but only the last two pairs of abdominal legs are present, 

 thus leaving the middle of the body unsupported. Hence, instead of 

 walking like many other caterpillars do, they move with a looping 

 gait and have been called "looping" caterpillars or "measuring worms." 

 Moreover, they have the habit of spinning a silken thread and letting 

 themselves down by it from the branches when the tree is suddenly 

 struck or jarred. Frequently they drop half way down to the ground 

 and remain quietly suspended in the air for a few moments, after which 

 they ascend to the branches above. It is said that during their great 

 abundance on the shade-trees in Brooklyn in the sixties much annoy- 

 ance was caused by this habit of dangling in the faces of pedestrians. 

 The following remarks of a committee from the Brooklyn Horticultural 

 Society anent this phase of the insect are interesting: " It would seem 

 to be entirely unnecessary for the committee to urge upon those who 

 have been constrained to traverse our streets in the latter part of June 

 and the early part of July, the great importance they might almost 

 say the necessity of devising and accomplishing some plan for remov- 

 ing the worms which dangle before their faces, are dropped upon their 

 clothing, or are crushed by their feet at every step. Certainly no gen- 

 tleman, no lady, can need to be convinced that carrying these worms 

 from house to house, brushing them out of the face and hair, or stopping 

 at the corners to pick them off with the fingers at the risk of crushing 

 them in the experiment is not a part of the privilege which one looks 

 for in becoming a resident of a city like this." 



Six caterpillars that emerged from eggs May 3rd began spinning 

 their cocoons May 30, July i, 2, 3, 6 and 7, respectively, and changed 

 to pupae about three days after commencing the cocoons. It should 

 be understood that these larvae were under exceptionally favorable 

 surroundings so far as food was concerned. The cocoons are very flimsy 

 affairs and usually are made by turning over the edge of a ragged leaf 

 and lining the inside with a thin net-like layer of silk (Fig. 56). Graef 

 and Weibe say that the insects pupate on the trunks and branches of 

 trees, on fences, railings, lamp-posts, or almost anything they can reach. 



The pupa is about five-eighths of an inch long, sometimes more, some- 

 times less. It is blunt and rounded at the anterior end but strongly 

 pointed at the posterior extremity and terminates with about six small, 



