Identification and management of swift moths in field crops

Swift moths include the ghost moth (also known as the ghost swift moth) and the common swift or garden swift moth. They are minor and localised pests of carrots, cereals and lettuce. The larvae cut off plants just below ground level or tunnel into roots or stems.

• The ghost moth is common in grassland, so any crop following a grass ley is most vulnerable to attack
• Lettuce is especially vulnerable to damage from the common swift moth

Common swift moth

Scientific name: Korscheltellus lupulinus (formally Hepialus lupulinus)

Adult common swift moths have a wingspan of 30–40 mm. They typically have dark brown forewings with white streaks that meet to make a ‘v’ shape, though some individuals are plain buff or brown with no pattern.

Larvae are white and the head is orange–red and well protected. They reach 30–40 mm when fully grown.

Ghost moth

Scientific name: Hepialus humuli

Adult ghost moths have a wingspan of 40–65 mm. The male is silvery white, and the female is pale buff, with a series of pale pink markings on the forewing.

Eggs are oval, shiny and white.

Larvae are like those of the common swift moth.

Common swift moth

Jun: Adult moths emerge in late May/early June.

Jun: Females lay about 200 eggs, dropped singly while the moth is flying.

Jun–Mar: Larvae feed underground, but severe damage occurs only during the late autumn and spring of the following year, especially in February/March.

Apr–May: Larvae pupate. The larvae of the ghost moth usually feed for 2 years before pupating.

Ghost moth

Jun–Jul: Adult moths emerge in late May/early June.

Jun–Jul: Females lay about 200 eggs, dropped singly while the moth is flying.

Jul–Apr: Larvae feed underground, but severe damage occurs only during the late autumn and spring of the following year, especially in February/March.

May–Jun: Larvae pupate. The larvae of the ghost moth usually feed for 2 years before pupating.

Non-chemical control

Cultivation may kill larvae.

Several polyphagous predators attack these pests, including birds and moles. The larvae may also be parasitised by certain species of wasp that eventually kill the larvae. The larvae continue to feed for some time after they have been parasitised, so crop damage is not reduced immediately. Larvae may also be killed by fungal disease.

To date, biological control has not been investigated in the UK.

Monitoring

Apart from the damage they cause, these pests are difficult to monitor.

Thresholds

None established in the UK.

Insecticide resistance

None known.