38 



of the soap and oil washes (17) ; hydrocyanic acid gas from one 

 ounce of potassium cyanide for each one thousand cubic feet of 

 space, left in the house over night (18); common laundry soap, one 

 pound to eight gallons of water (23 and 27) ; nicoticide (24) ; kero- 

 sene and resin washes (26) ; and hydrocyanic acid gas (for adults), 

 using 1 oz. of potassium cyanide for each 400 cu. ft. of space, ex- 

 posure of nine minutes (29). 



The experiments carried on at the insectary of the Massachu- 

 setts Agricultural College by the writer consisted of both spraying 

 and fumigation. The details of the experiments are first given, fol- 

 lowed by a discussion of results. When aphids or red spiders have 

 been present in noticeable abundance, the effect of the various in- 

 secticides on them has been incidentally noted, thereby showing the 

 comparative susceptibility of the Aleyrodes and other pests to the 

 same treatment. 



Contact Insecticides. 



Lemon Oil Insecticide. Mnfg. by S. I. Pollexfen, Baltimore, 

 Md. Cost: n to 25 cents per half pint, according to amount pur- 

 chased. Strength recommended: One-h'alf pint in from 4 to 12 

 quarts of water. 



1. One-half pint in 4 quarts of water. Plants treated : To- 

 mato, dipped in solution 20 sec; Petunia and Eupatorium, sprayed. 

 Results: Plants uninjured. About 50 per cent of immature insects 

 (excluding eggs) killed on Petunia and Eupatorium, and about 60 

 per cent on tomato plant. All adults hit by spray were killed, but a 

 large proportion escaped by flying away. Eggs not affected. 



2. One-half pint in 1 quart of water. Plant treated : Tomato, 

 dipped 20 sec. Results: Plant badly injured; all insects killed ex- 

 cept eggs. 



3. One-half pint in 1.5 quarts of water. Plant treated : To- 

 mato, dipped 20-25 sec - Results: Plant injured, though not as 

 badly as in previous experiment ; all stages of the insects killed ex- 

 cept the eggs. 



4. One-half pint in two quarts of water. Plants treated : Sin- 

 gle leaf of large tomato plant, dipped 10 sec. Lantana, sprayed. 

 Results : Tomato leaf slightly injured ; leaves of Lantana slightly 



