By Maria Gaura
This story originally appeared in the San Francisco Chronicle
SANTA CRUZ, Ca. - (July 2008) - There are pros and cons to any composting method, whether it employs soil bacteria, worms or black soldier fly maggots to do the job.
Maggot composting can work well if your household generates lots of food waste, if you raise chickens or if your yard is too small for a standard composting bin. Larvae can also be useful if you have lots of pet feces - including from dogs, cats, pigs and chickens - to dispose of.
It is disgusting but true that BSF will readily consume fresh animal droppings, neutralize the bad bacteria in those droppings and produce finished compost safe for your garden.
But maggots are less useful if you compost mostly yard trimmings or desire heaps of finished compost for gardening use. And don't add them to a worm composting bin, unless you wish to bid your worms adieu. BSF larvae won't eat live worms, but they will eat the ones that have starved to death in their company.
EVERYTHING BUT MAMMAL BONES
Karl Warkomski, who works for the recycling company ESR International, has kept a larvae bin for years at his North Carolina home. He composts not only his food scraps but also those of several neighbors, and he feeds the excess larvae to his chickens.
"I put everything in (the bin) except mammal bones," Warkomski said. "But everything else goes in: meat, dairy, enchiladas. Even chicken and fish bones get digested down, though that takes time.
"It's fun to get rid of all that food waste and end up with grubs to feed the birds," Warkomski said. "The songbirds love them, and my chickens are obsessed. I throw a handful in the yard, and they'll spend all day looking for them."
A thriving maggot bin reduces kitchen and restaurant waste by 95 percent, according to research conducted by ESR International. That means 100 pounds of food scraps will produce 5 pounds of soil amendment and 20 pounds of well-fattened larvae.
LARVAE ARE NUTRITIOUS
The soil amendment left by BSF can be added to garden beds or fed to captive worms. The larvae are nutritious feed for reptiles, pigs and farmed fish, as well as domestic poultry.
If left to their own devices, mature BSF larvae will crawl away from the colony to pupate, scattering in all directions as they find tiny nooks in which to hide.
ESR International has designed both home- and restaurant-size compost bins that provide little ramps for the departing larvae to ascend. Those ramps end in a drop-off that plops the migrating maggots into a collection cup, making it easier to use them as livestock or pet feed.
In warm-winter areas, maggot bins can be maintained year-round. BSF larvae thrive best at a temperature of 80 to 90 degrees, and languish or die at temperatures much more than 100 degrees. Adult flies need sunlight to breed, and home larvae bins must generally be left outside in a protected spot.
LARVAE ON A LARGE SCALE
While ESR International's larvae composters may appeal to garden hobbyists in the United States, the company hopes to have a larger environmental impact with large-scale municipal waste-disposal projects in warm-weather developing countries such as Colombia and Vietnam. Using maggots to consume food waste as well as animal and even human waste could greatly decrease the production of methane, a potent greenhouse gas.
"We sent larvae to a researcher in Iowa, and they actually made them into biodiesel," said Craig Sheppard, a retired professor of entomology and an expert on BSF. "If they divert their food waste, any fair-size city could set up a bioconversion plant" turning food scraps into renewable fuel.
For black soldier fly larvae, go to www.phoenixworm.com.
For black soldier fly information, larvae and composting supplies, go to www.thebiopod.com.
For ESR International's research on bioconversion using black soldier flies, go to www.esrint.com and click on Food.