293 



insects from iucreasiug to any serious extent by three applications at 

 intervals through the summer, but he cauuot expect to greatly reduce 

 then- numbers. Where three applications have been properly made 

 I have seen healthy scales as abundant on the trees upon the advent 

 of winter as they were in the month of April preceding. Our main 

 reliance must be either upon the gas treatment or upon winter washes. 

 Between November 20 and December 25, 1894, twenty-nine different 

 washes were most carefully applied to badly infested trees m Charles 

 County, Md. These applications were made either by Mr. Marlatt or 

 Mr. Coquillett, or by both together, and the writer was present at some 

 of the applications. The substances used and the results obtained may 

 be briefly stated as follows ; 



Whale-oil soap : 



1. Three pounds dissolved in one gallon of water. Fatal to all the scales on the 



trees sprayed with it. 



2. Two pounds in one gallon of water. Same result. 



3. One and one-half x>ounds in one gallon water. Fatal to ninety per cent of the 



scales. 



4. One pound in one gallon of water. Fatal to eighty per cent of the scales. 



5. One-half pound in one gallon of water. Fatal to one-half the scales. 

 Kesln wash : 



6. Six times summer strength. Resin, 120 pounds; caustic soda, 30 pounds; fish- 



oil, 15 pints; water sufficient to make 100 gallons. Fatal to all the scales 

 on the tree sprayed with it. 



7. Four times summer strength. Resin, 80 pounds; caustic soda, 20 pounds; 



fish-oil, 10 pints; water suflicient to make 100 gallons. Fatal to eighty-five 

 per cent of the scales. 

 Kerosene emulsion : 



8. Pure. Fatal to ninety per cent of the scales. 



9. One part of emulsion and one of water. Fatal to eighty per cent of scales. 



10. One part of emulsion and two of water. Fatal to one-half the scales. 



11. One part emulsion and three of water. Fatal to thirty per cent of scales. 



12. One part of emulsion in four of water proved fatal to only a small percentage 



of the scales. (On potted plants in Insectary.) 



13. One part of the emulsion in six of water, fatal to a very small percentage of 



scales. (On potted plants in the Insectary.) 

 Hard laundry soap : 



14. Two pounds dissolved in one gallon of water. Fatal to eighty-five per cent 



of the scales. 



15. One and one-half pounds in one gallon of water. Same result. 



16. One pound in one gallon of water. Fatal to sixty per cent of the scales. 



17. One-half pound in one gallon of water. Fatal to twenty per cent of scales. 



18. One-fourth pound in one gallon of water. Fatal to ten per cent of scales. 

 Concentrated potash lye: 



19. Two pounds in one gallon of water. Fatal to eighty-five per cent of scales. 



20. One pound in one gallon. Fatal to seventy-five per cent of the scales. 



21. One-half pound in one gallon. Fatal to one-half the scales. 



22. One-fourth pound in one gallon. Fatal to twenty per cent of the scales. 

 Fish-oil soap, homemade : 



23. One and one-half pounds in one gallon of Avater. Fatal to half the scales. 



24. One pound in one gallon. Fatal to twenty per cent. 



25. One-half pound in one gallon of water. Fatal to five per cent of the scales. 

 12283 -No. 4 2 



