ENTOMOLOGICAL SOCIETY OF ONTARIO. 67 



However, after this experience I was not surprised to find that the gentleman who 

 conducted the experiment which I am about to detail, desired his name, and particularly 

 his locality, to be kept from the public eye. I may state, however, that it is within two 

 hours' ride from the City of Washington, and that T have had an opportunity to verify 

 the condition of affairs as reported to me. 



The gentleman in question had seen in one of the newspapers some account of my 

 Catskill Mountain experiments and wrote to me through a mutal friend in Washington 

 for detailed advice in his own case. Correspondence elicited the fact that the mo.'iquito 

 supply must come from a small mill pond one-eighth of a mile from his house, from a 

 small, marshy track above the pond, and from two horse troughs, one at his barn and the 

 other at the roadside in front of his house. He had also a large rain-water Vjarrel for 

 which he immediately had a cover constructed at my advice. 



The horse troughs were readily freed from " wrigglers" by using a small fine-meshed 

 hand net every few days, and the kerosene treatment was used for the mill pond and the 

 marsh. Estimating the surface area of the pond at 4,000 feet, he sprinkled on it 15 gallons 

 of the cheapest kerosene. This formed a continuous layer, and remained evident to the 

 senses, in the absence of rain, for two weeks. Three weeks after the application, which 

 was made on the 4th of June, I visited the place and found that the kerosene was still 

 operative, although a slight shower had fallen on the 17th day. No trace of a living 

 aquatic larva of any kind could be found, and the surface of the pond was thickly strewn 

 with dead aerial insects, among them many female mosquitoes. 



A few straggling living mosquitoes were noticed about the house the first week in 

 June, but none subsequently, and although the treatment was not repeated, none have 

 been reported to have appeared during July. 



The small marsh pools above the dam were treated at the same time, two gallons of 

 kerosene being used for this purpose. The ensuing drought, however, dried these pools 

 uj) thoroughly and vitiated the experiment. The total expense of the treatment was .*$1.70 

 plus two hours light labor for two men, and the result was immunity from mosquitoes for 

 the household and vicinity. 



This is a typical case of those which I had in mind when I expressed last year the 

 opinion that there must be many localities where, by use of these simple remedies, the 

 mosquito plague may be averted. 



It may be well to add I had the pleasure of receiving, in May last, a note from Dr. 

 Robert H. Lamborn, the donor of the mosquito essay prizes of two years ago, in which 

 he says : " Your exact observation regarding the treatment of insect-breeding waters 

 with petroleum is most useful and it seems to me to be new." I trust it is understood 

 that no novelty is claimed for the idea, but that I have simply recorded these experiences 

 as showing conclusively that the remedy is not a theoretical but a practical one. 



Mr. Smith had known of two recent cases of the use of coal oil for destroying mos- 

 quitoes on Long Island, and stated that the results supported Mr. Howard's claims for 

 the method. 



Mr. Webster thought that the matter needed more experiment ; that there was a 

 prevalent opinion that mosquito larvas in pjnds appropriated a good deal of organic 

 matter that would otherwise become offensive, and by destroying them it was possible to 

 do harm instead of good. 



The Secretary read a paper by Dr. Ritsema Bos. on " Phytomyza affinis Fall, as a 

 Cause of Decay in Clematis." The larva of this little Hy he had found to produce a 

 disease spot on the stem a little above the level of the ground, causing the subsequent 

 drying up of the stem. He found two generations of the lly each year, and advised the 

 cutting off and burning of decaying stalks in early summer. Messrs. Hopkins and Gar- 

 man reported similiar appearances in potato stalks and the terminal twigs of apple, which 

 were probably due to a closely allied insect. 



