250 



TRANSACTIONS OF THE HORTICULTURAL 



three, twenty-seven per cent, in lot four, and eighteen per cent, 

 in lot five. 



Finally, May 17, a still more extensive experiment was begun 

 with London Purple, 347 curcuhos being divided into five lots, as 

 before, their treatment diifering from that of the foregoing only 

 in the substitution of London Purple for Paris Green. The results 

 were rendered, however, somewhat less satisfactory by the late- 

 ness of the season, which probably accounts for the number of 

 deaths in the check. Other parallel observations led to the con- 

 clusion that spent adults, doubtless the earliest to emerge, were 

 already beginning to die spontaneously. The experiment was 

 continued for eight days, when all the curculios of the first lot 

 were dead, and nearly all of the other poisoned lots, a fourth of 

 the check having also perished. 



EFFECT ON THE FOLIAGE. 



It is well known to fruit growers that the leaves of the peach 

 are much more sensitive to the scorching effect of the arsenical 

 poisons than those of the apple or plum, and it is important to 

 know just how strong a mixture of the common arsenical insecti- 

 cides that tree will bear under favorable, and also under unfavor- 

 able, conditions. My experiments on this point are incomplete, 

 but they are given here for what they are worth : 



First, two branches of a peach tree were sprayed, May 18, 

 with London Purple mixtures, a pound to 100 and a pound to 200 

 gallons, respectively. A week later no noticeable difference 

 could be made out between the condition of the two branches, the 

 tips of the leaves in both being somewhat deadened and dry. 

 May 20 identical applications were made, with no apparent effect 

 on the foliage by May 22. Heavy rains followed, and no further 

 observations were made. 



June 6, two other branches were sprayed as before. A heavy 

 rain followed June 8, and more upon the 9th. On the 10th, the 



