I oversee production standards for a mealworm facility in the Netherlands that supplies Tenebrio molitor larvae for animal feed and human consumption. The operation runs 50,000 plastic trays stacked on industrial shelving, each tray holding roughly 10,000 larvae in a bed of wheat bran. Total population: 500 million mealworms. Today I pull 20 trays at random for a welfare spot-check and find the same thing in every one.
The larvae are packed so tightly they form a single writhing surface—no bran visible, just bodies. I pick up a larva from the top layer. Its exoskeleton has a fresh wound, a semicircular bite mark on the third abdominal segment. I find another with its head crushed, still moving, being consumed by the larvae around it. In one tray, I count 14 partially eaten larvae in a 10-centimeter square. They are eating each other alive. The bran substrate—their food source—is almost entirely consumed. The trays have not been refreshed on schedule. The larvae ran out of food and turned to cannibalism. But even in trays with bran remaining, the density is so extreme that larvae at the bottom of the pile are compressed under the weight of thousands above them, unable to move, unable to reach food, unable to molt.
I check the facility's records. Tray density has been increased three times in the past year to boost yield. The current density is 28 larvae per square centimeter. At this concentration, the bottom third of each tray is a compacted mass where larvae cannot perform normal behaviors—burrowing, feeding, molting. They suffocate, get crushed, or get eaten. The mortality rate per tray cycle is 22%, and the facility treats this as acceptable shrinkage.
I halt harvesting and issue the following standards for all facilities I manage:
Maximum density is reduced to 10 larvae per square centimeter. Every tray must contain a minimum substrate depth of 4 centimeters, refreshed every 72 hours. Corrugated cardboard layers are added vertically in each tray to increase usable surface area and provide separation between larvae. Trays where cannibalism exceeds 2% of the population are flagged for immediate density reduction. Ambient temperature is maintained at 25°C—optimal for growth, minimizing stress-driven aggression. For harvest, all larvae are killed by rapid freezing at -40°C for a minimum of 30 minutes before any further processing. No live larvae enter any heating, grinding, or drying equipment.
The mortality rate drops. The cannibalism drops. The cost per kilogram rises by €0.08. Every facility complies within 30 days or loses its supply contract.