Encouragement and biology of rove beetles (a natural enemy of crop pests)

There are 1000 species of rove beetles (Family: Staphylinidae) in the UK, of which 40–50 are important for biocontrol.

Eggs are white and round or pear-shaped.

Larvae are elongate, with three pairs of legs, each of which has five segments with one claw.

Adults are of variable size (1–25 mm) and elongate with flattened bodies. They typically have short wing cases that do not cover the abdomen, although this is not unique to this family. Some have distinctive colours, usually red and black, and are easy to recognise (see Tachyporus hypnorum), but most are black and indistinguishable. Most species can fly and climb well. They can be confused with earwigs.

The breeding period of rove beetles varies between species. Smaller species breed earliest, from February onwards and continue through to winter. For most species, adults emerge between May and August. Depending on the species, they overwinter as larvae or adults. Larval stages are typically short – a few days to weeks – but the adults are longer-lived.

The diversity of species has resulted in a broad dietary range. It includes species that are scavengers, generalist and specialist predators, fungal feeders, leaf and flower feeders and parasitic.

Approximately 40–50 species are important for biocontrol, 5–10 are abundant on farmland.

In agricultural crops, the commonest species are omnivorous. The insect prey is frequently the eggs and larvae of flies, moths, butterflies, springtails and aphids. Rove beetles are consumed by other insects, amphibians, reptiles, birds and bats.

Once numerous on farmland, numbers have declined sharply in recent decades, especially fungal-feeding species, such as the Tachyporinae. This is possibly associated with fungicide use.

Rove beetles are especially vulnerable to insecticide sprays applied in the spring and autumn. Ploughing may not directly reduce numbers, but rove beetle abundance and species diversity is higher with minimal tillage, owing to indirect effects (more surface litter, weeds, soil moisture, fungi and detritivores).

They occupy most habitats, including crops, grassland and woodland. Rove beetles overwinter outside the crop in sheltered places, such as under rocks and bark or in grassy tussocks, or as larvae in the soil at densities of up to 500,000 per hectare.

The same methods used to encourage ground beetles will also favour rove beetles, especially reduction of all pesticide inputs because they are considered to be more sensitive.

For high value nursery crops, Atheta coriaria can be reared and released for the control of sciarid and shore flies – and potentially western flower thrips.