INSECT ATTACKS. 



Resistance of Fleas to Insecticides. 



That fleas are capable of resisting the effects of insecticides such as 

 will usually destroy insect life, is shown in the following communica- 

 tion received from a gentleman in Central New York, under date of 

 August 14th: 



Dear Sir. — I am in a quandary, and feel constrained to appeal to 

 you to help me out of my difficulty. About six or eight \^ eeks ago I 

 discovered that my cellar was infested with fleas, and 1 at once went 

 at them with a mixture of turpentine and gasoline, and supposed I had 

 exterminated the pests. About two weeks later I found they were still 

 jumping about, and I treated the floors with a solution of two ounces 

 cyanide potassium in one gallon water. Later, I used Persian insect 

 powder freely and an infusion of Cocculus indicus berries, one gallon 

 containing four ounces cyanide potassium. Then I again used the 

 insect powder, and gave my cellar two sulphur fumigations, using 

 three drams sulphur each time. I supposed 1 had really knocked 

 them out, until this morning, when I found that there were still a few 

 left to tell what they know about "hades." I have reached the limit 

 of my knowledge of insecticides applicable to fleas, and, if you can 

 suggest to me anything that I can use to rid my cellar of these rascals, 

 I shall be exceedingly indebted to you. My house is a new one, with 

 a well-lighted, airy cellar, and the fleas must have come from a Scotch 

 Collie dog that has slept in the cellar. I have almost concluded that 

 fleas will resist the action of any insecticide, for I noticed to-day a 

 number of lively fellows in a barrel standing outside of my cellar, that 

 had come up through sawdust that had been saturated with the fish- 

 berry and cyanide potassium mixture that I had swept up from the 

 cellar floors a couple of weeks ago. I am very anxious to rid my cellar 

 of these pests before my family returns from the country, and an early 

 response from you will be greatly appreciated. I remain, sir, &c. 



Reply was made of inability to recommend better insecticides than 

 those that had already been employed, unless, without endangering the 

 lives or health of his family, the infested cellar be charged with hydro- 

 cyanic acid gas [made by treating cyanide of potassium with sulphuric 

 acid]. It was probable that the larvie had been killed by the insec- 

 ticides used, and that the imagoes that were now appearing, in smaller 

 numbers than before, Avere those which had been sheltered and pro- 

 tected by pupation. 



