101 



1,000,000 specimens. With one-half gallon of oil this breeding place 

 was destroyed, whereupon almost com]:)lete relief at the hotel fol- 

 lowed. 



In shallow streams several feet wide and half a mile long the bot- 

 toms were so densely covered with larva? as to give them the appear- 

 ance of a dense covering of moss. Here sufficient black-flies emerged 

 daily to make life unbearable for an entire community. It required 

 only a few minutes to put dams across the streams to check and 

 deepen the water, as a result of which the larvae and pupae died. 



In Mount Washington brook the problem presents a different 

 aspect. Damming would be out of the question in most places on 

 account of the boulders and the great velocity of the current. Miles 

 of such breeding ground can be swe])t with a stable broom or raked 

 with iron rakes in one day. When such larva^ are loosened and 

 carried to deep water, they Avill die, but where shallow, nonihfested 

 water is ahead the operations may simply transfer the breeding 

 places. If in such cases a cheese-cloth net is stretched across the 

 stream, nearh^ all larvse can be captured. If a stick pointed at one 

 end is fastened to each end of the cloth, it can easily be adjusted to 

 streams of any width b}^ winding. 



Through experiments made at Dixville Notch and at Durham, 

 N. H., it was found that 5 gallons of oil poured in at the source of a 

 stream averaging 10 feet Avide and containing many shallow breed- 

 ing places would kill so many of the larva^ as to leave only an incon- 

 siderable number for a distance of 3| miles, and the water at the 

 end of a mile would not be too offensive for cattle to drink. Fish 

 apparently escaped doAvn the stream. 



As this species will shift its breeding grounds, it is not advisable 

 to make permanent dams, but instead cheap water gates may be 

 constructed which can be opened and closed at will. 



THE FUMIGATION OF A FRUIT HOUSE FOR CONTROLLING TEE 



CODLING MOTH. 



By A. F. Burgess, C'oln))ibHS, Ohio. 



Many larvte of the second brood of the codling moth (Carpocapsa 

 pomonella Linn.) do not emerge from the fruit until after it is 

 picked and placed in storage; hence it is usually possible to find 

 cocoons in the fruit boxes or in crevices in the fruit house during the 

 spring. Last April an examination of the boxes in which apples 

 were stored in a fruit house at Delaware, Ohio, disclosed the fact that 

 many larvse were present within their cocoons, and, as the building 

 was well constructed, an excellent opportunity was offered for test- 

 ing the effect of hydrocyanic-acid gas on this insect. After remov- 

 ing the fruit the empty boxes were allowed to remain in the house 



