Insects are in my box! What should I do?

In most cases, nothing.

Ants are commonly found in nest boxes, but if you specifically have fire ants (most common in the southern US) then we have tips to discourage them on our Dealing with Predators page.

Mites can also be found in nest boxes. Mites are ectoparasites, like some insects, ticks, and other small arthropods. There are beneficial mites (e.g., ones that eat dead skin off of birds’ feathers) and parasitic mites (e.g., those that feed on the blood of birds). In most cases, it’s best to leave them be. While we understand it can be distressing to find mites in your nest box, keep in mind that birds have evolved with the mites for millennia and have developed their own defenses to help guard against infestations. For example, House Wrens will sometimes add spider egg sacs to their nest materials, which is believed to help reduce mite infestations.

Never add chemicals, insecticides, or diatomaceous earth into nests, even if the nests are not currently active, as even small residues could harm the delicate nestlings. Furthermore, we don’t know how eliminating such parasites can affect the immune strength of nestlings. You can learn more about mites on our blog.

Often, insects or other arthropods that are found in nest boxes are harmless, though rarely mite or blowfly infestations may get bad enough to harm the nestlings. Recent research suggests that attempts by nest monitors to manage ectoparasites in their nests are not helpful to nestling survival, so it’s best to let things progress naturally.