As I approached a beetle perched atop a flower stalk, I noticed a large number of mites crawling all over it. Amazingly, the next day in a different location, I found the dead body of a vole with the same type of beetle burrowing under the carcass. It had several mites on it as well.
After searching for an identification of the insect, I learned more about this very interesting beetle and its relationship with the mites.
Here is a short summary of the beetle’s behavior and the mites’ role in helping its young survive.
The beetle is the Gold-necked Carrion Beetle, Nicrophorus tomentosus, who has sensitive antennae that contain olfactory organs that help it find carrion over long distances.
Once the body is found, the male and female beetles manipulate the carcass in various ways and then the female lays her eggs. The young eat directly from the carcass or eat regurgitated food from both parents. The parents are attentive to the young and protect them from competitors while they feed. The female only leaves the young once they are fully developed. If the female dies, then the male takes over that role.
The mites are Mesotigmatid mites who hitch a ride on the beetle’s back as it flies to the body of a dead rodent or other animal. They eat the eggs and freshly-hatched maggots of carrion flies which are also attracted to the body and, since they compete, having the mites feeding on the maggots is beneficial to the young beetles as it leaves more food for them.
Another fascinating fact: the mites normally cling to the beetle’s underside but when the beetle is about to fly, they all climb up on its back, facing forward. They are protected in this position because the beetle rotates its forewing coverings (elytra) up and toward the center, forming a tent-like enclosure with the mites inside.