August, '22] DAVIS : insect problems in Indiana 281 



beetle or shot-hole borer, Hessian fly and San Jose scale were reported 

 to us throughout the season. 



The peach tree borer {Sanninoidea exitiosa) has been the subject 

 of repeated inquiries which resulted from publicity given the new 

 PDB (ParaDichloroBenzene — Positive Death to Borers) treatment. 

 Oiu" experiments the past spring made in various sections of the state 

 from the extreme southern to the extreme northern end show that 

 spring appHcations (made during the month of May) are thoroughly 

 effective against the peach tree borer and may be used to advantage 

 where the fall applications have been neglected. We also found that 

 the sublimed or flaky form and granular were equally effective as was 

 also the crude granular. The latter was furnished us by the Inter- 

 national Chemical Company of Cleveland, Ohio. If regularly available, 

 it can be purchased at a much less price than the pure form and gives 

 just as good results. It was also determined after a number of tests that 

 treatment on sod ground was just as effective as where the ground was 

 cultivated. 



The Hessian fly (Phytophaga destructor) appeared in appreciable 

 numbers last spring, the first eggs being observed at LaFayette April 

 4. Although there was an appreciable infestation, it did not show up 

 conspicuously by fallen straws as is usual with these spring infestations. 

 Instead the spring brood of larvae killed the shoots while they were 

 small, the injury more nearly resembling the fall injury by the fly. 

 Heavy parasitism undoubtedly reduced the numbers for the fall genera- 

 tion appreciably but throughout the state wherever wheat was sown 

 earlier than a week before the recommended fly-free date, heavy in- 

 festation resulted. Fortunately, sowing wheat after the fly-free date 

 in Indiana was almost universal, and with good results. 



The San Jose scale {Aspidiotus perniciosus) is apparently increasing in 

 abundance in Indiana, necessitating further studies, particularly with 

 reference to the efficiency of the dry lime-sulphurs. The causes for the 

 increase are apparently due first of all to improper applications and 

 lack of thoroughness. Whether or not the spray gun has had its in- 

 fluence in this connection is a question which cannot be answered with 

 certainty at the present time but there is a tendency to do less thorough 

 work with the gun than with the rod. Other contributory causes are 

 probably, improper dilutions, time of applications, variable insecti- 

 cides on the market, and effect of parasites and predatory enemies. 



Tests were made the past spring in two localities in southern Indiana 

 to determine the relative efficiency of different dormant sprays now on 

 the market. Applications were made to apple late in the spring when 

 the buds showed pink, practically a delayed dormant spray. A stand- 



