Colobopsis explodens

Nuptial Flight Calendar

Flight months: Mar, Apr, May

Few ants capture the imagination quite like Colobopsis explodens, a species whose very name hints at its dramatic defensive secret. Described in detail by Laciny et al. (2018), this Southeast Asian formicine is a member of the cylindrica group, a radiation of “exploding ants” renowned for autothysis, the suicidal rupturing of the body wall to release sticky, irritant glandular secretions onto adversaries. The queen is a robust 8–10 mm in length, while workers exhibit a distinct dimorphism: minor workers range from 5 to 7 mm, with their characteristic phragmotic, plug-shaped heads, and the larger major workers, whose massively enlarged mandibular glands hold the chemical weaponry. Colonies are modestly sized, topping out at around 5,000 individuals, and they are strictly monogynous, founded claustrally by a single queen who seals herself away to rear her first brood without foraging. In the wild, C. explodens inhabits the canopy of dipterocarp rainforests across Borneo and parts of Sumatra, a region bounded roughly by 99° to 118° east and 5.5° north to 3.5° south, where they nest in pre-existing cavities in living trees, often in close association with epiphytic ferns. The combination of their phragmotic soldier caste, which blocks nest entrances with its shield-like head, and the explosive sacrifice of minor workers makes this a species of extraordinary behavioural and anatomical interest, but one that demands a keeper’s utmost respect and dedication.

Owing to a suite of demanding environmental requirements and a low tolerance for mismanagement, Colobopsis explodens is unequivocally an expert-level species. It is suited solely to experienced ant keepers who have successfully maintained other tropical arboreal ants with strict humidity and temperature needs, and who can provide unwavering stability. The colony’s small founding population and reliance on a single queen mean that any significant stress can be catastrophic. Novices should look elsewhere; even seasoned keepers will find this ant a humbling challenge. Its care difficulty stems not from aggression—the ants are not particularly prone to stinging—but from the precision required in recreating a pocket of Bornean canopy within a formicarium. Those who take it on must be prepared for daily monitoring and swift adjustments, as the window for recovery from desiccation or overheating is narrow. In return, the keeper gains a front-row seat to one of the most remarkable defensive adaptations in the animal kingdom, though witnessing a worker burst is a rare event that typically occurs only under severe threat, and should never be deliberately provoked.

Housing must mimic the warm, perpetually moist conditions of a tropical rainforest canopy. The optimal temperature range is 24 to 30°C, with a steady relative humidity of 70 to 90 per cent—a drop below this for more than a few hours will quickly lead to shrivelled brood and worker mortality. A temperature-controlled arboreal setup is essential. Glass or acrylic nests with a plaster, grout, or ytong substrate offer excellent moisture buffering; the nest should be vertical, with a hydration reservoir that can be topped up without flooding. Incorporate several smooth-barked, hollow branches or artificial tunnels of varying diameter to accommodate the size polymorphism; major workers will select tighter spaces near the entrance where their phragmotic heads can serve as living doors. A thin layer of leaf litter and decaying wood particles in the outworld helps maintain microhumidity and provides material for the ants to arrange. Because this species evolved as an obligate cavity-dweller, a naturalistic setup that includes small live epiphytes, though not necessary, can add enrichment and help stabilise the microclimate. Adequate ventilation is critical to prevent mould, but must be balanced against moisture loss; a small, computer-fan-driven air exchange on a timer can work wonders.

A varied diet rich in protein and carbohydrates is vital for brood development and the longevity of workers. In the wild, C. explodens forages for small arthropod prey and gathers hemipteran honeydew from the canopy; in captivity, offer small, freshly killed insects such as fruit flies (Drosophila hydei), pinhead crickets, and chopped mealworms twice to three times per week. Avoid wild-caught prey that may carry pesticides. Carbohydrates should be provided daily as a dilute honey-water solution or a specialised ant nectar, offered in small test tubes plugged with cotton or via a liquid feeder to prevent drowning. Protein and sugar sources should be placed in the outworld, never inside the nest. Water is best delivered through a permanently available drinking station—a water-filled tube with cotton—though the high ambient humidity will largely satisfy their needs. Dust food sparingly with calcium carbonate occasionally if the colony lacks access to natural mineral sources; this appears to support healthy cuticle formation in the major workers’ enlarged heads.

No hibernation period is required or desirable for this equatorial species. The ant originates from a region with remarkably uniform day length and minimal seasonal temperature variation, and it has no diapause phase in its annual cycle. The nuptial flights, which occur in Borneo around March to May following the rainy season (Laciny et al. 2018), hint at the only seasonal cue the ants respond to—a subtle shift in humidity and perhaps barometric pressure, but not temperature. In the artificial environment of the formicarium, maintain the same temperature and humidity year-round. Any attempt to induce a cool resting phase will likely be fatal. Instead, the keeper should replicate eternal late spring: days of 28°C, nights never below 24°C, and moisture always in the saturated range. This constancy must be maintained for the entire lifespan of the colony, which, with proper care, can thrive for many years under the queen’s reign.

When your C. explodens colony first arrives, the priority is to minimise stress and allow the ants to settle. The founding queen will likely be with a small batch of workers and brood, enclosed in a transport tube. Connect this tube directly to the prepared nest and outworld, but keep the entire setup dark and undisturbed for 48 hours except for a quick check to ensure hydration surfaces are wet and the temperature is correct. Do not feed immediately; the ants will still have internal reserves from the journey. On the third day, introduce a tiny amount of sugar water on a slip of paper in the outworld, retreat, and watch from a distance. If the workers discover it and return with distended gasters, you may cautiously offer a single freshly killed fruit fly the next day. Resist the urge to scrutinise them constantly; the first week is a critical window for brood production, and excessive vibration or light can cause the queen to cease laying. Watch for signs of the workers dragging brood into the outworld—a classic cry for more humidity. With patience and exacting environmental control, you will be rewarded by the slow, mesmerising expansion of one of the ant world’s most extraordinary societies.