Organic Value Recovery Solutions LLC
© Organic Value Recovery Solutions 2010
© Organic Value Recovery Solutions 2010
Soldier Fly Instead of Fish in Fish Feed
A Manuscript for
Gary J. Burtle
G. Larry Newton
D. Craig Sheppard
University of Georgia
After decades of work in Tifton, Georgia, University of Georgia researchers believe soldier flies will be a viable
alternative to fish meal in aquaculture diets. Early work with the black soldier fly (Hermetia illucens) used manure as
the growth media Recent efforts show that food byproducts are also an excellent media. Catfish grow well on soldier
flies. Other fish, including tilapia and rainbow trout have also been fed the prepupae. The most exciting opportunity
shows that changing the composition of the soldier fly diet will change the final composition of the soldier fly
prepupae in a value-added way.
Scientists in Asia, Europe, Israel, Australia, and North and South America have long proposed using insect
biomass as a high quality feedstuff for food animals including poultry, swine and fish. Insects, especially fly larvae,
can convert low value organic materials into protein and fat. House flies have been the most intensively studied in this
role because their biology is well understood and because of their high reproductive rate. But the house fly is a pest
and potential disease vector. Soldier flies are very different and present none of the house fly problems, but are more
efficient feed stuff converters.
Recent advances in black soldier fly culture make this insect the best candidate for industrial scale production.
Forty years ago massive populations of black soldier fly larvae lived under caged laying hens or swine housed in open
sided structures. A solid layer of larvae hundreds of feet long consumed manure as rapidly as it was deposited.
Manure residue removal was not needed for years since the migratory prepupae carried manure nutrients away as they
left the manure beds. These huge populations no longer exist because female soldier flies will not enter modern
enclosed animal housing. We can now to harness the productivity of this robust natural system.
The black soldier fly (Figure 1) is a great candidate for mass production. Adults are not pests, and larvae (Figure
2) tolerate and thrive at densities up to almost 3lb per sq ft (14kg/m2). Prepupae are self-collected as they leave the
larval mass to pupate, and are processed before developing into flies. With larvae maturing to crawl-off in four weeks
or less, high rates of production are possible in an intensive system. This will require scale-up and refinement of
systems suggested by 30 years of university research trials (Figure 3) and more recent commercial production of
Phoenix Worm larvae. Continuous production of Phoenix Worms R has been underway in Tifton, GA since 2005.
Larvae are reared on a grain diet and sold internationally as live food for captive reptiles and other small animals. Food
waste or fresh swine manure could potentially be fed to larvae at up to 2lb per sq ft per day. Feed conversion rates of
up to 25% (dry matter basis) should be attainable. Projections suggest that 1,000 tons of dry whole prepupae meal per
year could be produced using a 110,000 square foot facility. However, we expect the prepupae would be processed
into protein, fat (especially lauric acid), chitin and other products for best utilization.
Channel catfish (Figure 4) grew well on all diets containing soldier fly prepupae or skinless prepupae. Survival
during feeding trials was excellent and the presence of soldier fly up to 30% of the diet did not seem to change diet
palatability. Weight gain per fish remained similar among treatments up to the 30% addition level and no higher
inclusion levels have been tested (Table 1). The absence of negative results are remarkable in spite of the high chitin
content and high fat content of the soldier fly pre-pupae meal.
Although digestible energy in catfish diets was formulated to be approximately the same in all treatments, crude
fat content increased as the amount of soldier fly pre-pupae meal increased. Also, calcium and phosphorus content
increased with increasing amounts of the soldier fly pre-pupae meal. However, from practical considerations of the
addition of the new ingredient, addition of more than 7.5% soldier fly pre-pupae meal seems unnecessary. The
possibility of eliminating fish meal from catfish diets without a decline in performance is encouraging.
Soldier fly pre-pupae meal should cost less to obtain than menhaden fish meal. Fuel to capture, ship and process
menhaden fish meal would cost more than the cost of food byproducts used to produce soldier fly prepupae. Since
soldier fly prepupae are more than 40% dry matter, drying costs are expected to be less than for fish meal since fish are
20 to 25% dry matter.
Table 1. Channel catfish performancea when fed diets containing soldier fly pre-pupae meal. Means within rows were
not different from the reference containing menhaden fish meal, P<.05.
aData represent means of four tanks of fish per treatment held 20 fish per tank.
bBased on total diet cost times ratio of PER diet to PER reference with menhaden fish meal.
Figure 1. Black Soldier Fly (Hermetia illucens).
Figure 2. Soldier fly prepupae in dense culture.
Figure 3. Soldier fly prepupae growing in a pilot-scale facility.
Figure 4. Catfish feeding.