243 



fessor Agasslz and to other friends, with instructions and cautions 



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



vitse, 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 larvce 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 



beofin to show bare twio;s, and the foliage 



below was filled with masses of chippings, 



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 thouo-ht it hio;h 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 vitae. All the stragglers that could be 



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



