Blood-sucking insects, such as mosquitoes and black flies, often torment people who walk near bogs. Bogs are also rich in other kinds of invertebrates, such as day butterflies.

The larvae of butterflies eat the leaves of bog sprigs. For example, the larva of the moorland clouded yellow butterfly likes to eat the leaves of the bog bilberry, whereas adults of the same species use the flowers of bog sprigs as a source of nectar, simultaneously acting as pollinators. 

Bog insects are eaten by birds and other vertebrates, such as frogs and viviparous lizards. Frogs need bog ponds in order spawn and reproduce.

Viviparous lizards are common in open bogs and pine swamps. They can often be encountered sunbathing on warm, dry tufts of moss. 

Crane flies are bog-dwelling insects.