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1277 August 25, 1911

THE ABILITY OF FLY LARV.E TO CRAWL THROUGH SAND.

By Ch. Wardell Stiles, Professor of Zoology, and Harry McClure Miller, B. S.,
Assistant, Hygienic Laboratory, Washington, D. C.

Last year Stiles and Gardner published the results of certain
experiments on the burial of fecal material containing fly larvae.
They showed that if this material is buried under 48 or 72 inches of
sand, the flies will crawl to the surface and issue as adults.

A purely academic criticism might be raised against their experi-
ments, on the ground that part of the sand used had not been ster-
ilized. To meet this point, the experiments have been repeated
this summer with sand that was thoroughly boiled before using.
The results are as follows:

Experiment Jfi. — July 12 a pint of fecal material from a surface
privy in a typhoid locality and containing numerous fly larvae was
buried under 48 inches of sterilized sand in a standpipe which was
carefully cemented and screened. A Hodge flytrap was placed
inside the screen.

Adult flies were taken from the trap as follows:

July 21 80

July 25 655

July 29 6

Aug. 6 11

Total 752

Experiment Jfl. — On July 12 a pint of fecal, material from the
same privy was buried under 72 inches of sterilized sand, with the
same precautions from outside contamination.

Flies were taken from the trap as follows :

July 21 100

July 25 750

July 29 4

August 6 9

Total 863

The larval flies had crawled up and pupated near the surface. At
least two species of flies are represented in the material collected.
These have not yet been examined by any specialist on flies, but will
be sent to one for determination. One of the species appears to
agree with the common "housefly," "typhoid fly," or filth fly"
(Musca domestica) .

In connection with these two experiments the following observa-
tions are instructive:

Experiment Jfi. — Two Hodge flytraps were set for 24 hours, one
in the privy from which the feces for experiments 46 and 47 were
taken, the other in the dining room of the house, about 40 feet away
from the privy. At the end of 24 hours, 293 flies were taken from
the flytrap in the privy, and 1 ,742 flies were taken from the flytrap
in the dining room. These flies, which appear to us to be the common
house fly, have been sent to L. O. Howard, chief of the Bureau of
Entomology, for definite specific determination.




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