108 



and as the skins become cliy and are blown a])out by the wind the hairs 

 may 1)0 quite generally disseminated. When the hairs a lig"ht upon the 

 human skin the}' cause an irritation which, upon rub])iiig, ma}' develop 

 into inflammation. In New Hampshire this phase of the insect's pres- 

 ence has already become in evidence. At Portsmouth a clothes reel 

 was near a tree infested b}- the caterpillars. Tli(> family were oreatly 

 troubled through the summer by extraordinary irritations of the skin, 

 for which they were unable to account, but which were doubtless due 

 to caterpillar hairs blown from the pear tree. In the s ime cit}^ a 

 gentleman in removing a caterpillar which had landed on his neck 

 scattered some of the hairs, which produced an eruption similar to but 

 considerably worse than that produced by poison iv}'. 



The food preferences of the insect have been shown quite markedly 

 in our observations. Pear seems to be the favorite food plant, with 

 apple, wild cherry, plum, and hawthorn following along in about the 

 order named. 



AN EXPERIMENT WITH BLACK FLIES. 



By Cl.arexce 31. Weed, Durham, N. II. 



In the resort regions of northern New Hampshire the black flies 

 have long been recognized as one of the most annojnng pests for the 

 summer visitor, as well as for the resident citizen. I have had, from 

 time to time, appeals from hotel managers for help in subduing the 

 pest, but until this year haA'e had to confess that I knew of no probable 

 solution of the prol^lem. For several years I have had under ol)serva- 

 tion a colou}^ of black-fly larvw living on the flat rocks of the outlet 

 to our college reservoir, and have often tried to discover an effective 

 means of killing them. 



When studying the recent literature concerning mosquito remedies, 

 the property of phinotas oil, which leads it to sink to the bottom in 

 Avater, led me to think that possibly here we had an agent for destroy- 

 ing Sinmlion larva?. Last June, in order to test the theory, 1 sent 

 my assistant, Mr. A. F. Conradi. to Dixville Notch, N. H., where 

 these pests have for mau}^ years been especially troublesome, Avith 

 speciflc instructions to And the breeding places of the flies, and to 

 try the effect of the phinotas oil Avith Avhich he was provided. 



The Dixville Notch region Avas peculiarly favorable as to situation 

 for an extended experiment in subduing l)lack flies, for it is a compar- 

 ativel}' small area, surrounded by rnountains over Avhich no flies from 

 other localities would be likely to come. A large part of the encom- 

 passed area is taken up by a beautiful lake. Upon arrival Mr. Con- 

 radi made a careful survey of the entire locality, finding no flies 

 breeding in the SAviftly running shaded streams along the mountain 

 sides, but linding vast numbers breeding in shalloAv, sunlit Avaters at 



