ANNUAL REPORT, 1945-46 41 



Orchard Cage 



First Fly Emerged July 1 



25 percent of flies emerged July 8 



50 percent of flies emerged July iS" 



75 percent of flies emerged "..... July 19 



Last fly emerged .: August 5 



Percent of maggots which transformed 42.66 



Control of the Squash Vine Borer. (W. D. Whitcomb, Waltham.) Further 

 tests of the susceptibility of varieties of Cucurbitaceae indicated that all varieties 

 of Cucurbita moschata are immune to attack by the squash vine borer. In 1945 

 no infestation was found in the Cushaw, Longfellow Pumpkin, Alagold, Large 

 Cheese Pumpkin, Tennessee Sweet Potato, an'd Butternut varieties, all of which 

 belong to the species moschata. The infestation in four species of C. maxima 

 averaged 5.45 borers per vine, and in six species of C. pepo 3.47 borers per vine. 

 Cucumber, cantaloupe, and watermelon were also immune to attack by this pest. 



Biology and Control of the Celery Plant Bug. (W. D. Whitcomb and Wm. 

 Garland, Waltham.) Unfavorable weather conditions in May and early June 

 reduced the first generation of the celery plant bug, Lygus campestris L., to a 

 minimum and the results of experimental field studies were insignificant. 



The second generation was moderately abundant and caused severe injury in 

 the form of "black heart" to all of the untreated [ lants of the second planting of 

 celery. In the field where untreated celery was infested with 12 to 70 bugs per 

 10 plants, DDT-talc dust (containing 3 percent and 5 percent DDT) prevented 

 reinfestation for 2>?> days; and sabadilla-lime dust (containing both 20 percent and 

 50 percent sabadilla seed) gave protection for 14 to 19 days. These treatments 

 produced 70 to 80 percent Imarketable plants which were free of black heart at 

 harvest. Dusts containing pyrethrum and rotenone killed the celery plant bugs 

 but permitted reinfestation after 5 to 7 days. 



Biology and Control of the Grape Cane Girdler. (W. D. Whitcomb and Wm. 

 Garlano, Waltham.) In laboratorj- insecticide experiments, none of the canes 

 sprayed with DDT was girdled, and no eggs were laid on them.' Beetles confined 

 with DDT-sprayed canes lived about half as long as those confined with canes 

 sprayed with lead arsenate and cryolite. The number of feeding scars was re- 

 duced proportionately. The use of freshly cut terminal grape canes in cages 

 greatly simplified this type of insectary studies, compared with the potted grape 

 vines which were used previously. 



Sprays to Prevent Scolytid Infestation of Elm Logs. (W. B. Becker.) At 

 Springfield, the following spray mixtures were applied once to the entire bark 

 surface of elm logs before scolytids could attack them in the spring. The logs 

 used in the different tests were up to 8 and 14 inches in diameter with bark up to 

 one half and one inch thick. The percentages of prevention of scolytid infesta- 

 tion are based on the number of exit holes per square foot of bark in the late 

 fall as compared with unsprayed logs. Scolytiis muUistriatus Marsham was the 

 only or the predominant scolytid in the logs. The figures in parenthesis following 

 each spray mixture indicate the proportion of ingredients and the amount of 

 spray applied per square foot of bark. 



