Mussel Scale
Scientific group or name: Lepidosaphes ulmi
Overview
Mussel scale is an armoured scale insect that forms narrow, curved, shell-like covers on bark and branches.
Host plants
Apple and many woody fruit and ornamental plants.
Identification
Adult scales resemble small brown mussel shells attached firmly to woody tissue. Newly hatched crawlers are the mobile dispersal stage.
Damage and symptoms
Heavy infestations reduce vigour, contribute to branch dieback and encrust stems and fruiting wood.
Lifecycle and favourable conditions
Crowded woody growth and long-established infestations allow scales to accumulate over time.
Monitoring
Inspect trunks, branches and pruning wood. Monitor crawler emergence because this is the most exposed life stage.
Management
Prune heavily encrusted wood where appropriate, maintain tree vigour and avoid spreading infested propagation material.
Biological control and natural enemies
Parasitoids and predators may suppress populations. Conservation is important because adult scales are protected beneath their covers.
Biological control should be selected only after the pest has been identified and the crop, temperature, growing environment and pest pressure have been considered.
Related BioWiki pages
This page provides general integrated pest-management information. Identification and control decisions should be confirmed for the crop and local situation.