110 TEANSACTIONS OF THE ILLINOIS 



lime, for the codling moth and the cnrcnlios, the general result of 

 these experiments going to show that about two-thirds of the ajiples 

 subject to loss through the codling moth, and one-half those liable 

 to be destroyed by the curculios, might be saved b}'^ spraying eight 

 times with Paris Green. Last year was, however, an exceptional 

 year, the apple crop being very unusually light, following a good 

 crop of the year before. Moreover, eight times spraying was clearly 

 an excessive use of the poison, the arsenical compounds being pre- 

 sumably ineffective against the second brood of the codling moth 

 and certainly dangerous to health, if not to life, if used on the apple 

 after midsummer. Our work of last season was consequently incon- 

 clusive with respect to some important points, and I made this sum- 

 mer similar experiments, on a larger scale, intended to complete and 

 test the evidence of the year before; to try arsenic in solution in 

 comparison with London Purple and Paris Green; and especially to 

 test carefully and thoroughly the effect of a moderate number of 

 sprayings with poisonous insecticides applied onl}^ so early in the 

 season that there could be no possible question of danger to the con- 

 sumer of the fruit. I used this year Paris Green and a solution of 

 arsenic in comparison on eight selected trees. Two of these were 

 sprayed with a solution of white arsenic and six with Paris Green in 

 water, — two of the six sprayed once — May 11; two, twice — May 11 

 and 24; and two three times — ending June Tj. Companion trees were 

 selected as checks upon each of those thus treated, the check tree 

 being, of course, left unpoisoned. 



The Paris Green mixture was of the same strength as last year, 

 — three-fourths of an ounce by weight, of a strength to contain 15.4 

 per cent, of metallic arsenic, being simply stirred up in two and a 

 half gallons of water. The arsenic solution was made by boiling 

 one ounce of arsenic in one quart of water, and adding this solution 

 to twenty gallons of cold water. The method of procedure was pre- 

 cisely as last year, the trees being thoroughly sprayed with a hand 

 force-pump, and with the Deflector Spray and Solid Jet-Hose Nozzle, 

 manufactured by the Lowell Faucet Company, Lowell, Mass. 



The character of the season was the precise opposite of the year 

 preceding. Then a scant crop followed an abundant one; now an 

 •extraordinarily abundant crop followed a very scanty one. The 

 ratio of insects to the apples exposed to their attacks must have been, 

 consequently, doubly diminished as compared with that of 1885. 

 Further, our experiments were last year limited to early apples, no 

 late fruit being available; while this year only fall and winter varie- 

 ties were used. In these, finally, an additional brood of the codling 

 moth probably developed, making three in all for the season, while 

 last year we certainly had but two up to the time of harvesting our 

 experimental fruit. 



After spraying, the apples which fell both from the poisoned 

 trees and the untreated checks were regularly picked up at intervals 



