Sick stinging insects rarely stay home. Most leave their colonies voluntarily, and many never return. This behavior varies by species and by what’s making them sick, but the pattern is remarkably consistent: infected insects move away from their nestmates, seek out specific locations, and often die alone. Some are driven by instinct to protect the colony. Others are being manipulated by the very parasites or fungi that infected them.
Sick Bees Leave the Hive on Purpose
Honeybees practice what researchers call “altruistic self-removal.” When a worker bee becomes sick or compromised, it uses its remaining energy to fly or crawl out of the hive and simply doesn’t come back. This isn’t confusion or weakness. It’s a hardwired behavior shaped by evolution: sick bees that remove themselves protect the thousands of sisters they leave behind.
Workers infected with parasitic Varroa mites frequently fail to return to the hive after foraging trips. Bees with developmental deformities crawl out of the hive entrance on their own. Experimental studies published in the Journal of Evolutionary Biology confirmed that when bee health was compromised through different methods, the surviving foragers abandoned their social roles and permanently left their colonies. The researchers described this as “altruistic suicide,” and their theoretical analysis showed that natural selection broadly favors this behavior in social insects whenever a worker perceives it may be diseased.
The colony reinforces this from the inside, too. Nurse bees actively remove sick larvae and pupae from the comb, hauling them out of the hive. Just as healthy bees fly outside to defecate rather than soil the nest, sick adults use whatever energy remains to get themselves out the door. In winter, when flying isn’t an option, sick bees may crawl to the edges of the cluster or toward the hive entrance, dying at the periphery rather than near the queen.
Parasites Can Hijack Where Insects Go
Not all sick insects choose where they end up. Some are steered by the organisms infecting them, their behavior manipulated in ways that benefit the parasite rather than the host.
A striking example involves a tiny parasitic fly called Apocephalus borealis. Honeybees parasitized by this fly abandon their hives at night, which is highly unusual since bees are almost exclusively daytime fliers. Researchers at San Francisco State University first noticed something was wrong when they found stranded worker bees beneath streetlights and inside light fixtures on campus, even on cold, rainy nights when no other insects were active. These weren’t random stragglers. Testing confirmed the bees had been parasitized before leaving their hives and were being drawn to artificial light sources, behavior strikingly similar to what’s been documented in fire ants parasitized by related fly species. The parasitized bees die shortly after leaving, and fly larvae eventually emerge from their bodies.
This kind of behavioral hijacking appears across the insect world. The parasite benefits by getting its host to a location where the next generation can develop or spread more effectively, while the host has no say in the matter.
Fungal Infections Drive Insects to Climb
Some of the most dramatic examples of “where sick insects go” involve fungi that compel their hosts to seek elevated positions before dying. This phenomenon, called summit disease, has been documented since the nineteenth century.
“Zombie ant” fungi from the genus Ophiocordyceps infect carpenter ants and manipulate them into leaving their nests, abandoning their normal foraging routes, and climbing nearby plants or twigs. In their final moments, the ants lock their jaws onto vegetation at an elevated position and die there. The fungus then grows outward from the dead ant’s body, using the height advantage to release spores that rain down onto potential new hosts below.
This pattern repeats across many insect groups. Flies infected with Entomophthora muscae climb to high points as the infection progresses, extend their mouthparts to glue themselves to the surface, then raise their wings in a specific posture that helps the fungus launch spores toward other flies. Red wood ants infected with Pandora formicae end up attached to the tips of grass blades, with fungal structures bursting from their bodies. Grasshoppers infected with Entomophaga grylli climb to elevated perches where the fungus sporulates from their carcasses.
In every case, the fungus manipulates the host so that death occurs at an elevated location, giving the spores the best possible dispersal range. The sick insect isn’t choosing to climb. The fungus is, in effect, piloting the body to the spot that serves its own reproductive needs.
Sick Insects Seek Out Warmer Spots
Insects can’t generate their own body heat the way mammals do, but many sick insects do the next best thing: they move to warmer locations. This is called behavioral fever, and it works much like a true fever by raising body temperature high enough to fight off infection.
Research published in Science Advances showed this clearly in fruit fly larvae. Healthy late-stage larvae preferred cooler areas around 19°C (about 66°F). But larvae infected with parasitic wasps shifted dramatically toward warmer zones, congregating in areas between 25°C and 31°C (77°F to 88°F). The effect was consistent across four different wasp species. In one experiment, roughly 56% of infected larvae chose the 29°C zone compared to just 14% of healthy larvae.
This means sick insects may physically relocate to sun-warmed surfaces, heated rocks, or other warm microclimates that healthy insects would avoid. For stinging insects like wasps and bees, this could mean spending more time on sun-exposed surfaces or in warmer parts of a nest. The behavioral fever appears to be a genuine defense strategy, not a side effect of illness, since the temperature shift specifically targets ranges known to inhibit parasite development.
Pesticide Exposure Leaves Bees Stranded
Chemical exposure creates a different scenario. Bees that encounter certain pesticides while foraging don’t choose to leave the colony. They simply can’t find their way back.
Research on neonicotinoid pesticides found that only 9% of forager bees exposed to one common compound (imidacloprid) successfully returned to the hive within three hours, compared to 76% of unexposed bees. The pesticide disrupted the bees’ energy metabolism and hormonal regulation, effectively stranding them in the field. These bees end up wherever they happen to be when their systems fail: on flowers, on the ground, on nearby surfaces.
This is a different mechanism than altruistic self-removal or parasitic manipulation. The bees aren’t protecting the colony or being steered by an organism. They’re disoriented and unable to navigate home. The practical result, though, is similar: sick or compromised bees found alone, away from any nest, in locations that seem random because they essentially are.
Why This Matters for Colonies
The common thread across all these scenarios is separation. Whether driven by self-sacrifice, parasitic control, fungal manipulation, fever-seeking behavior, or chemical disorientation, sick stinging insects almost universally end up away from their colonies. For social species like honeybees, this spatial separation is a critical layer of disease defense. A colony of 50,000 bees living in close quarters would be devastated if sick individuals stayed inside and continued interacting with healthy nestmates.
So if you’ve ever wondered why you sometimes find a lone bee or wasp on the ground, moving slowly or not at all, far from any visible nest, this is often the answer. It’s an insect at the end of a one-way trip, either chosen or forced, that took it away from home for good.