finished feeding they will often leave the manure and pupate in the
ground below or crawl some distance away to pupate in débris under
boards or stones and the like. Hence the manure should be removed before
the larvæ reach the migratory stage; that is to say, removal is
necessary every three days, and certainly not less frequently than twice
a week during the summer months. A series of orders issued in 1906 by
the health department of the District of Columbia, on the authority of
the Commissioners of the District, covers most of these points, and
these orders, which may well serve as a model to other communities
desiring to undertake similar measures, may be briefly condensed as
follows:


HEALTH OFFICE REGULATIONS FOR CONTROL OF HOUSE FLIES IN CITIES.

All stalls in which animals are kept shall have the surface of the
ground covered with a water-tight floor. Every person occupying a
building where domestic animals are kept shall maintain in
connection therewith a bin or pit for the reception of manure and,
pending the removal from the premises of the manure from the animal
or animals, shall place such manure in said bin or pit. This bin
shall be so constructed as to exclude rain water and shall in all
other respects be water-tight, except as it may be connected with
the public sewer. It shall be provided with a suitable cover and
constructed so as to prevent the ingress and egress of flies. No
person owning a stable shall keep any manure or permit any manure
to be kept in or upon any portion of the premises other than the
bin or pit described, nor shall he allow any such bin or pit to be
overfilled or needlessly uncovered. Horse manure may be kept
tightly rammed into well-covered barrels for the purpose of removal