pound of calcium cyanamid plus 1/2 pound of acid phosphate to each
bushel of manure give an apparent larvicidal action of 98 per cent. The
mixture in the form of a powder was scattered evenly over the surface
and then wet down with water. The use of this mixture adds to the manure
two important elements, nitrogen and phosphorus.


MAGGOT TRAP FOR DESTRUCTION OF FLY LARVÆ FROM HORSE MANURE.

The second method of handling manure is one which does not require the
application of chemicals. It is based on the fact, mentioned on page 4,
that the larvæ of the house fly, a few hours before they are ready to
pupate, show a strong tendency to migrate. This migration takes place
mostly at night, and the larvæ sometimes crawl considerable distances
from the manure pile. Now it is possible by means of a very simple
arrangement called a maggot trap to destroy fully 99 per cent of all
maggots breeding in a given lot of manure. A successful maggot trap
which the Maryland Agricultural College constructed at the college barn
is shown in Figure 9. The trap was designed by R. H. Hutchison and
constructed under his supervision. The manure, instead of being thrown
on the ground, is heaped carefully on a slatted platform, which stands
about 1 foot high. This particular platform measures 10 by 20 feet.
There are six 2 by 4 pieces running lengthwise 2 feet apart. Across
these are nailed 1-inch strips with 1/2 to 1 inch spaces between them.
The wooden platform stands on a concrete floor, and a rim or wall of
concrete 4 inches high surrounds the floor. The floor slopes a little
toward one corner from which a pipe leads to a small cistern near by.
This pipe is plugged with a stopper of soft wood, and the concrete floor
is filled with water to a depth of 1 inch in the shallowest part. Flies
will lay their eggs on the manure as usual, but the maggots, when they