NICOTINE SULPHATE AS AN OVICIDE AND LARVICIDE. 5 



April 12 the eggs on each plate began to hatch, and later when 

 examined 42.1 per cent of those on the first plate had hatched; 60 

 per cent of those on the second plate and 92.7 per cent of those not 

 sprayed had hatched. On April 13 several dead larvae were found 

 on the sprayed plates and on the apples by these plates, but no dead 

 ones were found in the jar containing the control plate, and four bur- 

 rows were counted in the apple by this plate. On later dates it was 

 common to see dead larvae in each of the first two jars. On April 23 

 the plate sprayed with the solution 1 : 400 still emitted a faint nico- 

 tine-like odor. The apples by this plate showed four burrows, from 

 which finally emerged two full-grown larvae; those by the other 

 sprayed plate only one burrow, from which emerged a larva; and 

 those by the control plate also four burrows, from which emerged 

 two large larvae. Four of the five larvae passed through the pupal 

 stage and emerged as adult moths, while the fifth one only reached 

 the pupal stage ; this one was from the first two apples mentioned. 



The preceding tests indicate that nicotine sulphate is not an effi- 

 cient ovicide against the codling moth when the eggs are laid on glass 

 plates. Other experiments were performed by constantly keeping 

 fresh foliage of pear and apple trees in the battery jars. On the 

 third day after applying the spray solution a nicotine-like odor was 

 still emitted from the leaves, the strength of which depended upon 

 the strength of the solution used. This odor gradually disappeared, 

 and by the time the eggs began to hatch the observer could not per- 

 ceive it. Unsprayed leaves usually have bright and shiny surfaces, 

 but sprayed ones have dull surfaces, and with the aid of a hand 

 lens a dried film of residue from the solution may often be seen on 

 them. These experiments are summarized in Table I; experiments 

 1, 2, and 3 represent individual tests with eggs on pear-tree leaves, 

 while experiment 4 is a summary of several tests with eggs on apple- 

 tree leaves. Soap was used at the rate of 2 pounds per 100 gallons 

 of water. 



Kelative to experiment 4, the following notes, although not signifi- 

 cant, are nevertheless interesting. Four last year's apples, each be- 

 ing dipped into the same spray solution as that sprayed on the leaves, 

 were placed in four jars containing the sprayed leaves. Two apples 

 not sprayed were also placed in two jars containing unsprayed 

 leaves. Eliminating one of the four jars and its contents on account 

 of the apple in it becoming badly decayed before the eggs hatched , 

 245 eggs in the other three jars hatched and later 14 burrows were 

 counted in the three remaining apples. In the two jars used as 

 controls 52 eggs hatched, and later 14 burrows were also counted in 

 the two apples contained therein. Soon after this date all of these 

 apples totally decayed and consequently no matured larvae were ob- 

 tained from them. 



