ENTOMOLOGY AND PLANT QUAKANTLNK 
69 
formerly used, but there is iio indication that a moth-prcoting agent has yet 
been developed which imparts a permanent insect-resistant quality to the 
fabrics. 
Observations on the larder beetle indicate that the insect has only one 
generation a year in northern Vermont, whereas at Washington, D. C, several 
generations may be produced. The effectiveness of hydrocyanic acid gas in 
destroying this pest in large warehouses and in carload shipments of liver 
meal and other animal products to be used as fertilizers was demonstrated. 
MOSQUITOES 
Recent experiments have shown that paris green, when mixed with water 
and applied as a spray, is very effective for destroying the subsurface-feeding 
larvae of culicine mosquitoes. In a number of field tests with this arsenical, 
carried out under various conditions, high percentages of larval control have 
been obtained with several important economic species, including the salt- 
marsh mosquito Acdcs taeniorhuiKhi(s Wied., the fresh-water species Psoroyhora 
rolumhiac D. and K., and the southern house mosquito. Treatments were 
effective when the arsenical was applied with a sprinkling can or knapsack 
sprayer at rates as low as 1 pound per acre. Two preliminary tests were made 
with an autogiro as a means of applying the spray, and the results indicated 
that this type of airplane, with its comparatively low speed, could probably 
be adapted for treating large breeding areas that are not otherwise accessible. 
Samples of calcium arsenite having a comparatively high percentage of 
water-soluble arsenic were found to be nearly as toxic for mosquito larvae as 
paris gi-een. This product may therefore prove to be a satisfactory substitute 
for use in both anopheline and culicine mosquito control. "While this form of 
arsenical is apparently not yet available commercially, it seems probable that 
such a product can be produced at a cost appreciably lower than that of 
paris green. 
An acetone solution of phenothiazine was known to be much more toxic for 
mosquito larvae than the undissolved material. Recently it has been found 
that the addition of a sulphonated petroleum oil reduces greatly the amount 
of acetone solvent required, while providing a combination that is readily 
miscible with water. In preliminary laboratory experiments this solution 
gave 100-percent mortality in tests with larvae of Culex quinqiiefasciatus at 
a phenothiazine dilution as high as 1 to 2,000,000. 
A study was made of the distribution of the important tropical malaria mos- 
quito Anopheles aJhuufutus Wied., with .special reference to the possibility of 
its introduction into the Southeastern States. At present this species occtirs 
in the United States only in the lower Rio Grande Valley of Texas, and, judg- 
ing by the apparent temperature limitations there, it seems unlikely that It 
could survive in other portions of the Gulf Coast States except in southern 
Florida, where climatic conditions would appear to be favorable for its propa- 
gation if once introduced and allowed to become established. 
Sttidies on the biology and habits of the two floodwater mosquitoes Aedes 
(ildr^iehi D. and K. and A. vexans Meig. in the Pacific Northwest, particularly 
along the lower Columbia River, have shown that both species ami both 
sexes were dispersed in all directions, both with and against general wind 
currents, for a distance of from 2 to 5 miles from the breeding ground, and 
that there was a gradual dispersal up the tributaries of the Columbia River 
for distances of 8 and 10 miles. The extreme longevity of these species was 
112 days for females and 94 days for males. In years of low floods of the 
Columbia River — that is, about 10..5 feet — 73.4 percent of the mosquito popu- 
lation is Aedes vexans and 26.6 percent -4. aldriehi. In years of average high 
floods — about 19.7 feet — only 13.8 percent of the population is .4. vexans and 
86.2 percent .4. aldriehi. Studies of the factors influencing the hatching of 
eggs of these two species show that in the dormant stage they quickly lose 
their viability upon expo.snre to relatively long periods of inundation : that 
under normal conditions they may remain viable for at least 3 years in nature: 
and that overwintering eggs will not hatch when moistened with river or tap 
water but will respond (piickly when treated with various infusions, phos- 
phates, asparagine, and a number of other amino acids. These data have an 
important bearing on the type of mosquito-control methods to be used and 
should be taken into consideration in connection with any control work in 
areas where Aedes vexans and .1. aldriehi are serious pests. 
