10 



given a full account of this new discovery in the report which follows, it will be need- 

 less to more than call your attention to it in this place. * 

 As heretofore, I am indebted to yourself for suggestions and other help. 

 Respectfully, yours, 



D. W. COQUILLETT. 



Prof. C. V. Riley, 

 U. S. Entomologist. 



RESIN SOAPS AND COMPOUNDS FOR THE DESTRUCTION OF THE RED 



SCALE. 



Early in July of the present year I received a letter from Mr. L. O. 

 Howard, acting entomologist during the absence of Professor Riley, 

 instructing me to obtain permission from some person owning a number 

 of large-sized orange trees which were thickly infested with the Red 

 Scale (AspicHotus aurantii Maskell), and then have the trees sprayed 

 with one of the most approved resin sprays obtainable, the spraying 

 to be repeated as often as would be found necessary in order to prac- 

 tically free the trees of these pests, or at least to prevent them from 

 becoming so numerous as to interfere with the healthy growth of the 

 trees, the object sought for being to demonstrate that citrus trees badly 

 infested with these pests can be cleaned and kept in a healthy, grow- 

 ing condition by the use of the resin spray. 



Before entering upon this work I concluded to make a series of pre- 

 liminary tests with various preparations, containing resin and other in- 

 gredients in varying proportions, with a view of ascertaining the best 

 and most desirable preparation to use in my field work referred to 

 above. Accordingly I went down to Orange, in the adjoining county, 

 which bears the same name, and, on the 17th, 18th, and 19th of July, 

 made fourteen tests with various preparations, repeating one of these 

 and making several additional tests on the 7th and 8th of the following 

 month. The one giving the best results was used a trifle too strong, 

 as I subsequently ascertained that it produced a discoloration on the 

 underside of some of the oranges, or where they came in contact with 

 each other or with a leaf or branch. For this reason a slightly weaker 

 solution would produce better results, and doubtless the following pro- 

 portions will be found the most effectual to use during the hotter part 

 of the year : 



Resin pounds . . 18 



Caustic soda (70 per cent, strength) do 5 



Fish oil pints.. 2£ 



Water to make gallous . . 100 



The necessary ingredients are placed in the boiler and a sufficient 

 quantity of cold water added to cover them ; they are then boiled until 

 dissolved, being occasionally stirred in the mean time, and after the 



* This portion of Mr. Coquillett's report has been published in advance in Insect 

 Life, Vol. II, double No. 6 and 7 (January and February 1890).— c. v. R. 



