84 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



Table VIII indicates that a total of 580, or about 80 per cent, 

 of the 685 eggs hatched, but only 6 worms (about 1 per cent) 

 were able to penetrate through the lime-oil wash, enter the trees, and 

 finally mature to moths. Former experiments (see Table II) show a 

 higher percentage of fertile eggs. A great discrepancy between the 

 number of eggs which hatch and the worms which actually are able 

 to enter the trees had been previously noticed. There is also a great 

 mortality of larvsa, as is evidenced by the number of worms which 

 may be found in any tree and the number of moths that may mature 

 later. The almost complete immunity of these trees is not, therefore, 

 attributed entirely to the effectiveness of the lime-oil wash. 



Experiment No. 2. — The Wilson experiment was planned to deter- 

 mine the danger of injury by applying crude oils directly and in combi- 

 nation with lime to peach trees and also to determine the value of 

 these oils as repellents or barriers against the entrance of borers. 

 Crude oils have been applied directly to various fruit trees by orchard- 

 ists in the Santa Clara Valley, and their application has proved fairly 

 successful. Occasional injury has been reported. Peach and apricot, 

 and especially the younger trees of these varieties, are very sensitive 

 to oil, and it is believed that there must be more or less injury to other 

 trees. The crude oil is undoubtedly a most effective barrier to keep 

 newly hatched worms from entering the trees, and it also penetrates 

 and draws many more mature worms out to their death. The oils, 

 therefore, have a distinct and decided insecticidal effect against the 

 borers. 



The Wilson experiment was arranged in three plats — Plat I, with 



10 trees (numbered 1 to 10, inclusive), Plat II, with 5 (numbered 



11 to 15), and Plat III, with 10 (numbered 16 to 25). The earth was 

 removed, the borers dug out, and the bark scraped, as in experi- 

 ment No. 1. The various remedies were applied on June 20, 1908. 



Plat I was treated with the iime-oil mixture, which is recom- 

 mended as formula No. 1. It was applied just as it was used hi the 

 previous experiment. Three gallons of the mixture were sufficient 

 to treat the 10 trees. 



Plat II was treated with a light grade of pare crude oil known as 

 Coalinga crude oil, 22° Baume. This was likewise applied with a large 

 brush and in similar way to the lime-oil mixture. One gallon was 

 sufficient to treat these five trees. 



Plat III was treated with a heavier grade of oil known as Kern 

 crude oil, or about 14 to 16° Baume. This oil was cold and heavy and 

 rather hard to apply. Three gallons were sufficient to treat the 10 

 trees. 



The earth was immediately replaced around all of the trees after 

 the treatment. 



