The House Fly and How to Suppress It | Page 8

8 bushels of manure, or about 1 pound per 16 cubic
feet. Best results were obtained when the borax was applied in solution,

or when water was sprinkled on after the borax had been scattered
evenly over the pile. Borax is not only effective in killing the larvæ, but
when it comes in contact with the eggs it prevents them from hatching.
When applied at the rate of 1 pound to 16 cubic feet it was found to kill
about 90 per cent of the larvæ, heavier applications killing from 98 to
99 per cent.
Borax has no injurious effect on the chemical composition or rotting of
the manure. However, when added in large quantities with manure to
the soil it will cause considerable injury to growing plants. A number
of experiments have been conducted to determine the effect on crops of
the use of manure treated with borax as herein recommended. When
applied at the rate of 15 tons per acre it appears that no injury as a rule
will follow. Some crops are more sensitive to borax than others, and
also the tendency to injury appears to vary on different soils. It is
necessary, therefore, to repeat the warning issued in connection with a
previous bulletin[11] on this subject, that great care be exercised, in the
application of borax, that the manure does not receive more than 1
pound for every 16 cubic feet, and that not more than 15 tons of manure
so treated are applied to the acre.
In view of the possible injury from the borax treatment as a result of
carelessness in applying it, or from other unforeseen conditions, it is
recommended that horse manure and other farmyard manures which are
to be used as fertilizer be treated with hellebore. Borax, on the other
hand, is such a good larvicide that it call be used with advantage on the
ground of soil-floor stables, in privies, on refuse piles, and on any
accumulations of fermenting organic matter which are not to be used
for fertilizing purposes.
[Footnote 11: Department Bulletin 118, U. S. Department of
Agriculture, p. 25.]
TREATMENT WITH CALCIUM CYANAMID AND ACID
PHOSPHATE.
Many experiments with mixtures of commercial fertilizers were tried to
determine whether fly larvæ would be killed by any substance the

addition of which would increase the fertilizing value of the manure. A
mixture of calcium cyanamid and acid phosphate was found to possess
considerable larvicidal action. Several experiments showed that 1/2
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 have
finished feeding and begin to migrate, crawl out of the manure, drop
into the water below, and are drowned. Each week the plug is removed
from the pipe, and all the maggots are washed into the cistern. The
floor is then cleaned of any solid particles by means of a long-handled

stable broom