-24- 
million parts of water. In the same area limited observations were 
made on the effeot of 33DT on forest fauna in general* There was no 
evidenoe of mortality of bird life, but some of the fish and bull- 
frogs in the reservoir were killed* Most speoies of insects were 
greatly reduced in number, but 3 days after the spray had been 
applied enough specimens of most speoies remained to repopulate the 
area.—Dowden _et al . (136) j Craighead and Brown (126 ) • 
In Canada one 8-aore area was sprayed by autogiro with a solu- 
tion containing 10 percent of IDT in oyolohexanone and light petro- 
leum oil at the rate of 6 pounds of DDT per acre* Another area of the 
same size was similarly sprayed but at the rate of 4 pounds of DDT 
per aore. Very little significant difference of effects was notioed 
between the two areas* Along the lake shores and in quiet pools a 
few minnows were killed by contact with the oil film when they broke 
through the surface to feed upon insects brought down by the spray* 
In the stream the emulsified DDT solution became too diluted to be 
toxic to minnows or speckled trout* However, speckled trout seem to 
be more sensitive to DDT, as any that fed on poisoned insect larvae 
and adults falling into the stream were killed* Aquatic inseot lar- 
vae that remain submerged in quiet waters were not affected by the 
DDT spray. However, mosquito larvae and suoh surface forms as water 
stridors and whirligig beetles were readily killed. In the streams, 
where the solution becomes mixed with the running water, or lodges 
under partly submerged rocks, the larvae and nymphs of aquatic in- 
sects, such as the dragon fly, damsel fly, may fly, caddis fly, stone- 
fly, midge, cranefly, blackfly, beetle larvae (Dytisoidae, Psephenidae), 
and fishfly (Sialldae) nay be completely eliminated* Crayfish and tad- 
poles were readily killed by contaot with the spray or by ingesting 
contaminated food* As these are important sources of fish food, their 
destruction would no doubt have an unfavorable influence on fish sur- 
vival within the streams* Clams, snails, and leeches were not affect- 
ed by the sprays* The cyolohexanone and the oils used in the sprays 
were not in themselves toxie*— Ross (30 6) • 
In field experiments with DDT mosquito larvicides, BDT in con- 
centrations sufficiently high to kill subsurfaoe feeding larvae was 
toxic to the following three speoies of fish: 
Blaok Bass*— A spray of diluted kerosene emulsion containing 0*1 
percent of DDT proved fatal within 3 day6 after application* 
Catfish*— In a pond sprayed with diluted oil emulsion containing 
0*2 percent of DDT many catfish were dead 2 days after treatment* 
Salt-water minnows*— Dead fish were found in salt-iaarsh test holes 
2 days after treatment with a oolloidal solution of 1 part DDT to 
4,000,000 parts of water. 
