243 



fessor Agassiz and to other friends, with instructions and cautions 

 respecting them. In my little place, I have but a single Arbor 

 vita3, a magnificent specimen ; it was above fifteen feet high, 

 a dense and graceful pyramid from bottom to top of deep green 

 foliage, and so planted as to be a pleasing and conspicuous 

 object from the parlor windows. For a long time I looked for 

 the larvns in vain. During the whole of June, and the early 

 part of July, my time was so entirely given to the Library 

 (this being my busiest season of the year) that I hardly thought 

 of the tree and the drop-worm at all. It was not till the 

 twentieth of July that I was at liberty to 

 make a careful examination of it, and then 

 to my surprise I discerned vast numbers of 

 the insects upon it, but principally at the 

 very summit, where they had begun the 

 work of destruction in earnest. It seems 

 that the greater part of the worms, soon 

 after being hatched near the bottom of the 

 tree, made their way to the top, so that 

 they escaped observation until carefully 

 looked for. Already the top of the tree 

 began to show bare twigs, and the foliage 

 below was filled with masses of clippings, 

 looking like brown saw-dust. The pods 

 were not more than three eighths of an 

 inch long, of a conical shape and green color, and were 

 often borne vertically above the body of the insect, like a 

 shell on the back of a snail. Within a week, the insects 

 began to appear plentifully near the lower part of the tree, 

 and I thought it high time to diminish their numbers, and 

 began killing all I could reach from the ground. Some of the 

 insects were carried, apparently by the wind, to neighboring 

 trees, and some were found on an apple tree above a hundred 

 feet from the Arbor vitse. All the stragglers that could be 

 found were promptly killed, and I set my little son at work on 



Fig. 29. 



