4 THE AUDU BOW BUD Dee 
control of adult mosquitoes and larvae was noted in the August and 
September sprayings. The drift from adjacent unsprayed areas hastened 
to repopulate the area and numbers were so restored as to make retreat- 
ment necessary at 30-day intervals. The effect on other insect species was 
likewise very pronounced, and their absence reflected in the presence of 
insectivorous birds. 
Birds 
No dead birds were found which could be traced to mortality by DDT. 
A fresh, partly eaten pied-billed grebe was noted by Biologist Smith on 
a point bordering the slough near the highway, but the death pointed to 
predators. Two normal grebes and a wood duck were observed on a 
slough nearby. 
A nest of catbirds with three young was kept under observation for 
36 hours, but no noticeable effect was apparent. The young left the nest 
as normal birds do and were not again seen. 
Goldfinches nested along the Bellevue Dam, and while not located, the 
adult birds were observed busily carrying insects: to the young. As this 
was on the border of the sprayed area, insects were brought from the 
outside. The day following the first spraying, three flycatchers were 
observed chasing the same lacewing. 
It was apparent that with the sharply reduced insect population, 
some shifting of bird populations would be made. After the first spraying, 
from the third day insect eaters began to desert the sprayed area. By 
September all the insectivorous birds had left the area, with the exception 
of the woodpeckers. Noticeably absent were swallows, flycatchers, warblers, 
vireos, redstarts and thrushes, although these birds were in normal numbers 
off the sprayed area. Particularly noticeable were the swallows feeding 
above the dam and along the Mississippi proper. Near Station No. 5, 
which apparently was missed by the October spraying, chickadees and 
flycatchers were seen. Little dependence was placed on October bird 
populations as migration was in progress. One flock of over 100 rough- 
winged swallows was seen on October 3 flying through the sprayed area, 
but it was noted that no feeding was done. The normal number of fish- 
eating birds was present throughout, including bald eagles, ospreys, 
egrets, blue and green herons. Biologist Smith and I observed about 
2,000 wood ducks in small flocks fly from the sprayed areas into the lotus 
beds above the Bellevue Dam on October 3. 
Mammals 
As previously noted, the raccoon population was exceptionally high in 
the wooded areas of the Depot, while the crayfish were nearly wiped out 
by DDT. Apparently it caused no mortality, as the sign was as abundant 
in October as in August. I observed one female and two half-grown young 
feeding on sick crayfish about 11:00 am., the next day after the first 
spraying. After 15 minutes of observation, when one young had eaten a 
dozen crayfish, I captured it and held it for 10 minutes to note any toxic 
effects. In October it was noted that the raccoons had changed their 
