Brown Tail

Overview

The Brown-Tailed Moth (BTM) is a defoliating insect pest known for its harmful caterpillars, which are covered in toxic, urticating hairs that can cause skin irritation, rashes and respiratory issues in humans and animals. Effective treatment and control are essential in both public health and tree health contexts, particularly in urban or high-traffic areas.

Lifecycle and Risk Timing

• BTM caterpillars overwinter in silken webs or nests on host plants, particularly blackthorn (Prunus spinosa), hawthorn (Crataegus) and fruit trees.
• From spring through summer, caterpillars emerge and feed heavily, causing significant defoliation and shedding of hairs.
• Human health risk peaks during this active feeding phase, especially in dry, windy conditions.

Control and Treatment Methods

1. Manual Removal of Nests (Primary Method):
• Winter to early spring (November–March) is the ideal time to remove and destroy overwintering webs before caterpillars become active.
• Nests are cut or pruned from branches by trained operatives wearing full PPE, including gloves, goggles and respirators.
• Removed material is securely bagged and disposed of as hazardous waste (e.g., via incineration).
2. Insecticidal Treatment (If Required and Permitted):
• During the early larval stages (April–May), targeted application of a biological insecticide (e.g., Bacillus thuringiensis var. kurstaki) may be used.
• Applications are carefully controlled to minimise harm to non-target species and are typically restricted to publicly accessible or high-risk areas.
• Chemical treatments must be conducted by licensed professionals in accordance with pesticide regulations.
3. Public Safety Measures:
• Signage and temporary exclusion zones may be installed to protect the public from exposure.
• Educational notices may be issued to local residents if infestations occur near housing or schools.
4. Monitoring and Follow-up:
• Affected sites are monitored seasonally to detect re-infestation.
• Long-term management may include habitat modification, selective planting or promoting natural predators to reduce BTM populations

Health and Legal Compliance

• Works are carried out under COSHH and PPE regulations, with attention to public health guidance.
• Contractors handling BTM must be trained in safe nest removal, pesticide application (if used) and biohazard control.
• In high-risk areas, collaboration with local authorities or public health officers may be required.