330. 
In general the laboratory tests gave better results than the 
tests, a fact which can be attributed to differences in boll 
coverag wind, rain, exposure to sunlight, and other variable 
factors. In some of the field plats the ea infestation was 
so heterogenous that but little confidence can be placed in the 
results. ‘The results may be briefly summarized as follows: 
1. In the loboratory tests only 4 of the 12 insecticides re~ 
duced the number of worms per boll over the checks enough to be cones 
sidered significant, viz, sodium fluoaluminate 59.55 percent, barium 
fluosilicate 44,09 percent, rotenone 56.9 percent, sodium fluosil- 
icate 76.65 percent, and derris 88.95 percentreduction. 
ave 2th ee field tests only two of the 10 materials tested gave 
significant.reductions. These were sodium fluosilicate 25.95 percent 
on the stepped-up infestation and 41.1 perce: itreduction on the natur- 
al infestation, while the corresponding reductions for derris were 
23.38 percent ond 49.36 percent. 
3. Invpetri dish. tests to determine contact action, the only 
significant result secured with the 9 substances tested was with 
derris, which killed 99.4 percent of the larvae in 3 hours. Rotenone 
and sodium fluosilicate caused only a slightly higher mortality than 
he check, 
4, In the oviposition tests, a distinct preference was always 
shown for the undusted bolls, either beceuse of the repellent action 
of the ee or by its making the boll surface unfavorable for 
oviposition. e bolls dusted with Cerris decreased the total ovi- 
position toa aoe amount and no eggs were laid on the dusted 
bolls. Moths in the Gerris cages became inactive and the average 
longevity wes sonewant reduced. Moths suspended in cages from plants 
in the field and dusted with heavy applications of 5 percent nicotine 
sulphate end free nicotine were not kilied. 
INSECTS AFFECTING MAN AND ANIMALS. 
Civil Works ee SERLLENS s discc oe eases --The large- _scale mosquito~ 
control project under Federal c ction by this Division and financed 
from an allotment. of funds by rate “ WA was brought to a close on 
February 15. A comparatively small force of men are continuing the 
work already begun upon the tract set aside for the National Arboreteum 
in the District of Columbia. 
While the major work in mosquito control was done along the 
Atlantic and Gulf coasts, where the salt-marsh mosquitoes are of great 
economic importance, a number of inland States such as Tennessee, 
Ohio, Indiana, Illinois, and Iowa. undertook work, particularly in 
the vicinity of centers of population. This project appears to have 
