106 



were yet alivej but no adults had issued. I added 10 cc from the stock 

 and in a few minutes all the pupte were dead. 



In other words, a mixture of 1 to 10,000 will kill larvae, but it 

 requires one 5 times as strong to kill pupa^. 



"CRETOL, MASSLIGEK NO. 1." 



This is one of the preparations sent me by Mr. F. B. Kilmer, presi 

 dent of the New Brunswick board of health, and it was tested on the 

 larva? and pupsie of Culex puiKjcns only. 



At a dilution of 1 to 8,000 it killed all the larv^se in a few minutes 

 and all the pupte in an hour. 



"CRETOL, HA8SLIGER NO, 2." 



This material is riot so readily soluble as the No. 1 and forms an oily 

 or tarry surface film. I made the usual stock of 1 to 100 and tried it 

 on Culex pungens only. I added 5 cc of the stock to 500 cc of water 

 containing larvffi and pup*, and in a few minutes all larvse were dead; 

 in half an hour the pupte also had succumbed. 



Both of these preparations are very fatal to pupaj compared with 

 some of the others previously reported. 



SOLUBLE CREOSOTE. 



This also was sent me by Mr. Kilmer. It mixed readih^ with water, 

 forming the usual milky emulsion, and was reduced to the usual 

 stock, 1 to 100. It was used on Cidex pimgens only in jars containing 

 500 cc of water. 



To jar No. 1 1 added 5 cc of stock at 10.30 a. m. At 2.45 p. m. 

 many larvie were yet alive, all pupa; wei-e active, and many adults 

 had issued. It was only upon young larvie that this mixture had any 

 ill effects. 



To jar No. 2 I added 10 cc of stock at 10.30 a. m. At 2.45 p. m. 

 all larvw and some pupa? were dead, while one adult had emerged. 

 No more adults emerged later, and all pupa? were dead next morning. 

 At 1 to 5,000, therefore, soluble creosote is a good larvicide. 



"CRESOL, 100 PER CENT." 



This is one of the materials referred to as coming from the stock of 

 Johnson & Johnson, but is not a product of their manufacture. All 

 their samples mixed readily with water, and were purer grade mate- 

 rials than any of the preceding. 



I reduced the cresol to 1 to 100 and added 5 cc to 500 cc of water 

 containing larva? and pupa? of Chdex pungens. Eighteen hours later 

 only the small larvje were affected: some of the mature larva? had 



