16 



BULLETIN 571, U. S. DEPARTMENT OF AGRICULTURE. 



For some reason, presumably because the twigs were kept in too 

 dry a condition, many larvae failed to emerge from hibernacula that 

 were not treated, as is shown in Table IX. The best results were 

 obtained with undiluted miscible oil, while strengths ranging from 

 1 :12 to 1 :20 gave considerably less benefit for the treatment, as 

 was also the case when 10 and 20 per cent kerosene emulsions were 

 employed. Commercial lime-sulphur solution at 1 :8 and 40 per cent 

 nicotine sulphate at 1 :32 ranked second in effectiveness. 



Further dipping tests were made with commercial lime-sulphur 

 solution on March 26, 1914. The strengths employed were 1:8 and 

 1 :10, in which thirty heavily infested pecan twigs were dipped, and 

 after the treatment the twigs were caged immediately in jars and 

 placed in the out-of-doors insectary. By March 31 many of the 

 larvae were emerging from their hibernacula and feeding upon the 

 developing buds. Further observations showed that lime-sulphur 

 at these strengths was not effective in preventing many larvae from 

 emerging from winter quarters. 



Table X shows further dipping and spraying experiments with 

 lime-sulphur and miscible oil. 



Table X. — Dipping and spraying experiments for destruction of hibernating larvae of the 

 pecan leaf case-bearer at Honticello, Fla., in 1916. 



Experi- 

 ment 

 No. 



II 

 III 



rv 



Treatment. 



Dipped twigs in commercial lime- 

 sulphur solution (1:8), testing 32° 

 Baume\ 



Sprayed twigs with commercial lime- 

 sulphur solution testing 32° Baume\ 



Sprayed twigs with miscible oil at 1:15. 



Check; twigs untreated 



Date of appli- 

 cation. 



Mar. 7, 1916 



.do. 



.do. 



Result. 



Many larvae emerged and destroyed 

 every bud. 



Many larvae emerged and destroyed 



most of the buds. 

 Many larvae emerged and destroyed 



practically every bud. 

 Larvae emerged and readily destroyed 



every bud. 



The twigs used in these experiments were kept in water or moist 

 soil in order to insure the proper development of the buds. The 

 first observations were made on April 17, 1916, and results as shown 

 in Table X indicate the condition of the f oliage. It will be noted that 

 the lime-sulphur and miscible oil failed to destroy the larvae. 



SPRAYING EXPERIMENTS i FOR THE DESTRUCTION OF LARVAE IN HIBERNATION. 



A series of spraying experiments was conducted with several of the 

 standard winter sprays to find out their effect upon larvae in hiber- 

 nation, and in all cases the material was applied thoroughly by means 

 of a gasoline-power outfit. 



1 The spraying was done in bearing pecan orchards belonging to the Standard Pecan Co. and the Summit 

 Nurseries, both of Monticello, Fla., and to Mr. Charles E. Pabst, of Ocean Spring, Miss. 



