It all started with the can’t-tear-your-eyes-away video of black soldier fly larvae devouring a 16-inch pizza in just two hours. Watching sped-up action of the writhing mass inspired mechanical engineer Olga Shishkov of Georgia Tech in Atlanta to see what makes these insects such champions of collective feeding.
An individual Hermetia illucens larva doesn’t eat steadily, Shishkov found. One feeds for about five minutes on average and then stops for about another five. As a group of thousands, though, they flow continuously like a living fountain splashing up against the edge of their food, Shishkov and colleagues report February 6 in the Journal of the Royal Society Interface.
Shishkov borrowed techniques from the study of fluids, for instance treating larvae as particles moving with a current, and looked for overall patterns of flow in a writhing mass of as many as 10,000 insects. She tracked the directions larvae were wriggling and found that, around a chunk of food, a fountainlike flow develops.
Fount of food
A surge of black soldier fly larvae (left) surrounds a piece of an orange. At the center, they create a living fountain (schematic cross section at right) as the incoming larvae toward the bottom push those closer in that have paused in eating upward and out of the way. The motion spins the food (curling arrow at top) as the larvae jostle one another.
As larvae took a break from binging, the hungry crowds pressing from behind forced them upward. Those at the top then fell away from cliff-face of food. This up-and-out push lets a larva eager to feed replace one that’s taking a break.
The voracious feeding of black soldier fly larvae isn’t just nature as entertainment. The larvae define edibility broadly — pizza, garbage, animal waste, it’s all good. So people searching for ways to make food systems more sustainable wonder whether there’s an opportunity to recapture what would usually be wasted by letting the larvae devour it and in turn, feeding them to chickens or other animals that people eat. That’s certainly one reason to embrace a species that not only eat garbage but can handily murder a pizza. Also, Shiskov says, “they’re the cutest maggots I’ve ever seen.”