43 



however, is quite likely to be broken before the ground is reached. 

 This habit of dropping to the ground when disturbed, as they 

 undoubtedly often are by birds or by the branches swaying in the 

 wind, probably, as Weed has stated, accounts in part, at least, 

 for the large numbers of caterpillars that are seen crawling up the 

 trunks of infested trees. Observations upon caterpillars in con- 

 finement showed that much less silk is spun after the last molt 

 while crawling about than during the earlier stages. 



Sharins; a nest with the apple-tree te^it- cater pillar. — What is 

 probably a very unusual occurrence is shown at Plate III, fig. i. 

 This nest was made by a colony of apple-tree tent-caterpillars. 

 It will be observed that most of the caterpillars in sight are not 

 the rightful owners of the nest, but are forest tent-caterpillars. 

 The two species can be easily distinguished as the apple-tree tent^ 

 caterpillars have a conspicuous white line extending the whole 

 length of the back, while the forest tent- caterpillars have the line 

 replaced by a row of white spots. This nest was on an apple 

 tree near the Station grounds. At the time this picture was 

 taken, about 10:30 a. m., the caterpillars had collected on the 

 sunny side of the nest. There were none on the opposite side. 

 The writer watched this nest for several days and it was observed 

 that the "guests" went out regularly with the other species 

 to feed and returned with them. Upon no occasion, however, 

 were the forest tent-caterpillars seen to enter the nest. Upon the 

 fourth day the nest was cut open and although it was well filled 

 with apple-tree tent-caterpillars none of the forest tent-cater- 

 pillars could be found. A few days after these observations were 

 made Mr. G. G. Atwood reported finding a similar case in an 

 apple orchard a few miles distant. Although it is not uncom- 

 mon to find two or three stray forest tent-caterpillars upon 

 one of the nests of their near relatives, such cases as the 

 above appear to be quite unusual. 



Congregating habit.— h. very noticeable habit is that of con- 

 gregating in large numbers on the trunks and branches of the 

 infested trees. There appear to be two principal occasions for 

 this, first, when resting during the heat of the day and, second, 

 when about to molt. As an indication of the former, the writer 

 has observed the caterpillars disperse toward evening after having 



