ANNUAL REPORT, 1040 67 



Introduction of Parasites of Oriental Fruit Moth in Peach Orchards. 



(A. I. Bourne.) This service, requested and financed b}- peach growers 

 of the State, was continued in 1940, and more than 30,000 Macrocentrus 

 ancylivorus were liberated in the orchards. Through the cooperation of the 

 Department of Entomology of the Connecticut Experiment Station, Mr. 

 A. DeCaprio was again secured to take immediate charge of this work 

 from June 1 to July 15. More than 80 colonies of Macrocentrus parasites 

 were released in the orchards of 63 growers in 9 counties of the State. 

 Several of the county agents assisted in the release of the parasites and 

 enabled the work of liberation in the orchards to be done with greater 

 dispatch than Avcaild otherwise liave been possible. As a result of the 

 efficient work of Mr. DeCaprio in the collection of breeding material in 

 New Jersey and improved technique in the laboratory, the percentage of 

 emergence was so very high that it was posMble to supply parasites for 

 all advance orders and furnish to the county agents enough colonies to 

 duplicate orders. The Laboratory also supplied colonies to Dr. Christo- 

 pher, extension horticulturist of Rhode Island State College, for the 

 peach growers of that state on the same terms extended Massaclnisetts 

 growers. Many growers availed themselves of the ofifer made this year 

 to furnish colonies in two containers. This allowed, in separate blocks or 

 different parts of the same orchard, distribution of parasites with the 

 proper proportion of sexes for satisfactory colonization. 



During the period when the parasites were liberated weather condi- 

 tions were favorable for their activity, and little or no mortality was noted. 



Naphthalene and Similar Compounds as Greenhouse Fumigants. (W. 



D. W'hitcomb and A\'m. Garland. Waltham.) A complete series of thirty 

 experimental fumigations of potted carnations was made, using a mixture 

 of chlornaphthalene oil 3 parts and crystal naphthalene 1 part, at the rate 

 of 1/2 ounce per 1,000 cubic feet for 6 hours. 



One treatment gave complete control of the common red spider 

 (Tctranychus felarius L.) at a controlled constant temperature of 80° F. 

 and constant relative humidities of 80 or 90 percent. At temperatures of 

 60° and 70° F.. and relative humidities of 80 and 90 percent, the mortality 

 of red spiders ranged from 80 to 90 percent; while at 50 percent relative 

 humidity tlie mortality varied from 50 to 83 percent. 



After two successive fumigations, complete mortality resulted at 50 

 percent relative humidity with a constant temperature of 80° F. ; at 60 

 percent humidity with constant temperatures of both 70° F. and 80° F.; 

 and at 70 percent humidity or higher at all three temperatures. 



These results were obtained only when the controlled temperature 

 and relative humidity were maintained throughout the entire period of 

 exposure. 



Control of the Common Red Spider on Greenhouse Plants. (VV. D. 

 Whitcomb, Wm. Garland, and W. E. Tomlinson, Jr., Waltham.) Life- 

 history studies under controlled conditions indicated that female 

 red spiders {Tctranychus tcJarius L.) on carnations developed from newly 

 hatched larvae to adults in 16.91 days at 60° F., 10.22 days at 70° F., and 

 6.07 days at 80° F. The same development took approximately one day 

 less on sweet pea and one-half day less on snapdragon than on carnation. 

 This difference was consistent at constant temperatures of 60°, 70°, and 

 80° F. As observed in previous studies, the developmental period at 60° 

 F. was about three times longer than at 80° F. 



