considerations before choosing a compost
method)
fly control
One of the most important problems in composting
is controlling flies. Garbage, animal manure,
tomato and several other food-processing
wastes, are excellent media for breeding
and development of large fly populations.
If adequate control measures are not practiced,
particularly when composting manure, the
compost systems will be infested with extremely
large numbers of flies, and create a health
hazard.
Fly breeding can be controlled in composting
operations during the fly season, with little
more effort than is normally necessary for
good sanitary composting. Added manure and
fresh food scraps in the composting systems
should be kept covered.
Fly larvae in composting material may originate
from eggs laid in the material at the place
of collection or from eggs laid during the
handling of the material at the compost site.
If the latter were the main source, fly control
would be no problem. However, much of the
material is infested with eggs and larvae
in various stages of development, sometimes
even at the pupal stage, before arriving
at the compost site. Therefore, material
must be prepared immediately for composting
and placed in compost systems where high
temperatures and environmental conditions
are unsatisfactory for continued emergence
of flies.
The predominant species of flies encountered
in composting will vary with the area and
with the type of material. The variety of
materials available for composting offers
satisfactory breeding conditions for many
different species, but generally speaking,
the compost operator does not have to worry
about the particular species, since the most
satisfactory control measures in composting
apply equally well to different species.
The life cycle of the ordinary housefly,
"musca domestica," is usually from about 7 to 14 days
when conditions are favorable. The time of
the different stages varies with temperature
and other conditions, but on average it may
be considered as follows: egg, 1 to 2 days;
larva 3 to 5 days; pupa, 3 to 5 days; emergence
of young fly, 7 to 10 days; and egg laying
by new fly, 10 to 14 days. Fly control measures
must interrupt this cycle and prevent the
adult flies from emerging.
Some procedures, particularly grinding, turning,
and systematic cleanliness, which are useful
in providing compost of good quality and
in destroying parasites and pathogens, are
also effective for controlling flies. Initial
shredding or grinding to produce material
more readily attacked by bacteria also destroys
a large number of the larvae and pupae in
the raw material. Also, the texture of material
shredded to a maximum size of 2 inches is
not as suitable for fly breeding.
Studies at the University of California on
mixed garbage and refuse demonstrated that
after raw material containing considerable
numbers of eggs and larvae had been ground
and placed on the pile, no fly breeding took
place using normal composting procedures
of turning every 2 to 3 days. Apparently,
the destruction of the larvae by grinding,
mixing, and the structural changes caused
by grinding, results in garbage that is no
longer attractive to flies. Heat quickly
generated in compost piles effectively stops
flies breeding in refuse containing a considerable
proportion of garbage. However, this is not
the case, for compost materials containing
large amounts of animal manure, food scraps
and other fresh and decaying fruits.
When materials attractive to flies and containing
large numbers of larvae and pupae are composted,
some of the larvae will move to other cooler
layers and continue their life cycle. The
most effective method of destroying these
larvae is frequent turning. Turning compost
stacks at daily interval, when the raw material
contains many larvae and pupae and when fly
breeding conditions are favorable, and at
a maximum interval of 3 or 4 days when fly
breeding conditions are not especially favorable,
provides good fly control.
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