ANNUAL REPORT, 1943-44 33 



minute for the 100 hens in the pen and recirculating about 500 cubic feet of air 

 over the litter. The litter that year had about the same moisture content in 

 all three pens. This arrangement produced more floor draft than was desirable, 

 so a smaller fan was installed for 1943-44 with a circulation of only 150 cubic 

 feet per minute over the litter. This apparently was not sufficient to keep the 

 moisture content of the litter down to that in the other pens. Another attempt 

 will be made during the coming season to obtain sufficient circulation to keep 

 the litter dry without creating an objectionable floor draft. No attention was 

 given to adjustments or changes in the ventilation of the fan-ventilated pen 

 either season, a feature which is of considerable interest to the poultryman. 



DEPARTMENT OF ENTOMOLOGY 

 Charles P. Alexander in Charge 



Investigation of Materials which Promise Value in Insect Control. (A. I. 



Bourne and W. D. Whitcomb.) Work on the cooperative project was continued 

 with attention focused on several lines of research. 



Tests were made to study the effect on apples of adding DN-1 1 1 to the standard 

 spray combination of lead arsenate and wettable sulfur in the regular applica- 

 tions immediately following bloom. The calyx application (May 27), made 

 under conditions of moderate temperature and humidity and followed by similar 

 weather conditions, caused no injury whatever. The first cover spray (June 3), 

 however, was followed by general and quite conspicuous burn, which was most 

 extensive on Baldwin and Greening and considerably less on Wealthy and Cort- 

 land. By mid-July the falling of the worst affected leaves and development of 

 new growth had very nearly obliterated any evidence of injury. No appreciable 

 cut in yield was noted. 



On July 20 and August 9 sprays were also applied to peaches, pears, plums, and 

 cherries in the college orchard and no ill effects were noted. Temperature in the 

 period following the spra3's rose to 80° or above. 



Applications of DN-1 11 and D-4 to approximately 20 different types of decid- 

 uous ornamentals indicated that during June these materials, even at moderate 

 temperatures, caused moderate to serious injury in most cases; while in late 

 July and August similar applications, even at temperatures as high as 84°, caused 

 no evidence of any damage to foliage, almost without exception. 



Counts of red mite made 24 hours after application of D-4 dust showed 56 

 mites per 100 leaves compared with 2296 mites on leaf samples taken just before 

 dusting, a 97 percent reduction. DN-1 11 at IJ^ pounds to 100 gallons in similar 

 tests gave 95 percent reduction, and at 1 pound to 100 gallons, a 98 percent re- 

 duction. The difference in results was due to the density of foliage and difficulties 

 in securing thorough coverage in the case of the trees given the 1 J^-pound dosage. 



Summer applications of dinitro materials are often coincident with the presence 

 of honeybees working the blossoms of cover crops in the orchard. Beekeepers 

 are very sensitive to the possibility of losses from sprays and dusts, and every 

 new material used for insect control becomes an object of suspicion. In tests 

 to determine the effects of dinitro compounds on bees, D-4 dusted on honeybees 

 caused only slightly greater mortality than occurred on normal bees in the same 

 length of time. When compared with rotenone, nicotine, or pyrethrum dusts, 

 the toxicity of D-4 was very low. DN-1 11 (at a dilution of 13^ pounds to 100 

 gallons) in a sugar solution proved to be more toxic, foe all the bees in the test 

 died within 5 days. 



