Strength-mass scaling law governs mass distribution inside honey bee swarms.

To survive during colony reproduction, bees create dense clusters of thousands of suspended individuals. How does this swarm, which is orders of magnitude larger than the size of an individual, maintain mechanical stability? We hypothesize that the internal structure in the bulk of the swarm, about which there is little prior information, plays a key role in mechanical stability. Here, we provide the first-ever 3D reconstructions of the positions of the bees in the bulk of the swarm using x-ray computed tomography. We find that the mass of bees in a layer decreases with distance from the attachment surface. By quantifying the distribution of bees within swarms varying in size (made up of 4000-10,000 bees), we find that the same power law governs the smallest and largest swarms, with the weight supported by each layer scaling with the mass of each layer to the [Formula: see text] power. This arrangement ensures that each layer exerts the same fraction of its total strength, and on average a bee supports a lower weight than its maximum grip strength. This illustrates the extension of the scaling law relating weight to strength of single organisms to the weight distribution within a superorganism made up of thousands of individuals.

Black Soldier Fly Larvae Rearrange under Compression.

Thousands of black soldier larvae hatch simultaneously from eggs laid within rotting vegetation or animal carcasses. Over the next few weeks, they grow while compressed by both their surroundings and each other. When compressed, these larvae rearrange to reduce the forces upon them. How quickly can larvae rearrange, and what final state do they choose? In this experimental study, we use a universal testing machine to conduct creep tests on larvae, squeezing them to set volume fractions and measuring the time course of their reaction force. Live larvae come to equilibrium at a rate 10 times faster than dead larvae, indicating that their small movements can rearrange them faster than just settling. The relaxation of dead larvae is well described by stretched exponentials, which also characterize hierarchical self-avoiding materials such as polymers or balls of crumpled aluminum foil. The equilibrium pressures of live larvae are comparable to those of dead larvae, suggesting that such pressures are dictated by the physics of their bodies rather than their behavior. Live larvae perform fluctuations to actively maintain this equilibrium pressure. This ability to survive large pressures might have applications in the larvae-rearing industry, where both live and dead larvae are packed in containers for shipping.

Black soldier fly larvae feed by forming a fountain around food.

The black soldier fly is a non-pest insect of interest to the sustainability community due to the high eating rates of its edible larvae. When found on carcases or piles of rotting fruit, this larva often outcompetes other species of scavengers for food. In this combined experimental and theoretical study, we elucidate the mechanism by which groups of black soldier fly larvae can eat so quickly. We use time-lapse videography and particle image velocimetry to investigate feeding by black soldier fly larvae. Individually, larvae eat in 5 min bursts, for 44% of the time, they are near food. This results in their forming roadblocks around the food, reducing the rate that food is consumed. To overcome these limitations, larvae push each other away from the food source, resulting in the formation of a fountain of larvae. Larvae crawl towards the food from below, feed and then are expelled on the top layer. This self-propagating flow pushes away potential roadblocks, thereby increasing eating rate. We present mathematical models for the rate of eating, incorporating flow rates measured from our experiments.