172 BOARD OF AGRICULTURE. [Pub. Doc. 



in our region, so I could get it in every stage. I had very 

 careful experiments performed upon them in every moult. 

 AVhat I mean by that is, the insect changes from the egg to 

 a little minute caterpillar, which grows a certain time and 

 then its skin splits and it crawls out of thai ; it grows larger, 

 the skin cracks again and it crawls out of that, and so on. 

 That is, it moults several times. This moulting is rather 

 a critical period in the history of the insect ; it is more 

 likely to die in that period than any other. I put them 

 on some branches of an apple tree, and put the branches 

 in cages where the insects could not get away, and where 

 I could sec just what transpired. Then I sprayed them 

 with Paris green in each stage or moult from the time 

 they were hatched until they were ready to spin their 

 cocoons. I used one pound of Paris green to fifty gallons 

 of water, one pound to seventy-five gallons, one pound to 

 one hundred and fifty gallons, one pound to two hundred 

 gallons, one pound to three hundred gallons, and so on up 

 to one pound to a thousand gallons ; and they died under 

 the application of either proportion. That is, one pound of 

 Paris green to a thousand gallons would kill them, but it 

 took about a week to do it. I found the most satisfactory 

 result was when I used about one pound to three hundred 

 gallons of water. I got as good results with that pro- 

 portion as I did with any larger proportion. Furthermore, 

 one pound to three hundred gallons of water will not injure 

 the foliage of an apple tree in any sense whatever. 



I have tried another series of experiments. (These 

 things are not yet published, but they will appear in the 

 bulletins of the Hatch Experiment Station.) I had twelve 

 apple trees set out in the greenhouse connected with the 

 insectory, which is divided into two parts. One of those 

 parts was kept as warm and muggy as possible, while the 

 other part was kept dry and cool, so that we might have 

 two dilferent climates. The apple trees were as nearly the 

 same size as we could get them. They were set out the 

 year before, so that they got well established. When the 

 leaves had come out on the trees they were all showered 

 with Paris green, one pound to one hundred and thirty 

 gallons. It was my intention to burn the foliage, because I 



