41 



bark of the tree and in very few cases was there any attempt at a 

 shelter. 



From accounts in the papers of that date it would seem that the in- 

 sect prevailed throughout the forests of the Northwest, and in some 

 instances, while moving in armies from one locality to another, they 

 were so numerous on railroad tracks as to occasion delays and stoppage 

 of trains. Poultry refused to feed upon them, and, so far as I was able 

 to observe, very few birds attacked them. My stay was not sufficiently 

 prolonged to enable me to ascertain what proportion of the larvae were 

 destroyed by parasites. I was informed by friends who were summer- 

 ing at Lake Minnetonka that one still, warm evening early in July all 

 the moths seemed to issue at once and were so numerous that the flut- 

 tering of their wings up and down the trunks of the trees and among 

 the branches filled the air with a distinct and peculiar humming sound 

 that attracted very general attention and curiosity. 



On the succeeding evening scarcely a moth could be seen, and it was 

 supposed that the brisk wind that blew during the day had carried 

 them into the lake. So far as I could judge by their behavior in the 

 rearing cage, they develop with remarkable regularity, hatching, molt- 

 ing, and transforming simultaneously, so it is probable that in one or 

 two evenings of winged existence they had fulfilled their mission of 

 providing for the continuance of their kind. 



NOTES ON SOME NATURAL ENEMIES OF PERNICIOUS INSECTS. 



The Web-worm Tiger (Plochionus timidus) (if I may be permitted to 

 give it a popular name) realized all that was anticipated of it this sea- 

 son in its work of exterminating the insect it has selected for its special 

 prey. 



June 6 I found two colonies of Hypliantria cunea, one on a young tree 

 of Box Elder and the other on a vigorous sprout of Laurel Oak, both in 

 excellent position for observation in situ. The larvae in each case had 

 inclosed but two or three leaves and seemed to be about ready for the 

 first molt. 



On the 10th a single specimen of Plochionus was observed running 

 up and down in each of these webs. On the 16th a close examination 

 of the nest revealed a dozen or more of the slender white eggs attached 

 to the twigs and petioles of the leaves and a few laid loosely in the 

 web. On the 20th larvae about 3 mm in length were seen in the web and 

 probably others had attached themselves to the Web Worms, now about 

 ll mm , or one-half inch in length. 



When next visited, June 23, the colony on Box Elder had migrated 

 and separated into three companies on different parts of the tree. 

 They had not, however, in this way escaped their relentless foe, for a 

 number of the active little Oarabids were running about among them 

 apparently quite at home wherever the Avorms were. Two were seen 



