BUREAU OF ENTOMOLOGY. 217 



grate very little, the insects may be reduced greatly by the destruc- 

 tion of their favorite food plant, the service tree. Various paints 

 and washes have been tested, and several of them have been found to 

 be effective against borers. 



Evidence has been gained which indicates that what is called " stig- 

 monose injury " to apples is connected with the punctures of the 

 fruit by aphids, particularly the rosy aphis. Spraying experiments 

 in orchards for the control of the rosy aphis resulted in a consider- 

 able diminution of the stigmonose injury. 



Important biological studies of several species of apple aphids 

 have been carried on. Further experiments in the use of poisonous 

 gases against the woolly apple aphis in orchards have been made. 

 Carbon bisulphid may 'be applied to the roots by injection or in 

 water poured around the roots. Many tests have been made to deter- 

 mine the dosage which will be effective against the insect and safe 

 to the trees. An essential part of this investigation has been the 

 determination of the effect of soil temperature and soil moisture on 

 the diffusion of the gas, as well as the behavior of the gas in various 

 types of soil, as in clay, shale, or sandy soil. 



Grape iNSECTS.^The biological studies of the grape Phylloxera in 

 California have been concluded, and manuscript is in course of prepa- 

 ration for publication. Renovation experiments in vineyards have 

 been continued, and show that by the use of deep plowing, fertilizers, 

 and, when possible, irrigation, much benefit may be derived. In 

 cooperation with the Bureau of Soils, investigation of the relation 

 of Phylloxera injury to different types of vineyard soils was con- 

 tinued. This information will be valuable to prospective planters. 



Field experiments in the control of the grape-berry moth in the 

 Lake Erie Valley have been continued, and the use of arsenical 

 sprays, hand-picking of the infested fruit, and the covering of the 

 fallen infested foliage in vineyards by fall plowing have been tested. 

 Best results in control were found to follow applications of arsenate 

 of lead at the rate of 3 pounds of the paste to 50 gallons of water, 

 applied immediately after falling of the grape blossoms and about 

 two weeks later. Both of the other methods mentioned, however, are 

 valuable adjuncts to the more effective spraying work. Some work 

 upon this insect was done in cooperation with the Ohio State Agri- 

 cultural Experiment Station at Sandusky, Venice, Put in Bay, and 

 Kelleys Island. 



Peach insect investigations. — Work on the peach-tree borer has 

 been continued, and special attention has been given to experiments 

 in orchards with the use of various poisonous gases to destroy the in- 

 sects in their burrows around the base of the trees. It seems that 

 from 95 to 100 per cent of the borers can be killed by the application 

 to the roots of from one-eighth to one-fourth ounce of carbon 

 bisulphid in 1 gallon of water. No injury has been noted from the 

 use of this substance at these strengths, although injury results to 

 trees under certain soil conditions from the use of an ounce or more 

 of carbon bisulphid per tree. The relation of soil moisture and of 

 temperature and physical conditions of the soil to the use of this 

 substance is being thoroughly investigated. 



Nut insect investigations. — Investigations of pecan insects, with 

 headquarters at Monticello, Fla., have been continued with success; 



