Woolly apple aphid

Eriosoma lanigerum 

1. Identification

• Common name: Woolly apple aphid
• Scientific name: Eriosoma lanigerum Hausmann
• Order: Hemiptera
• Family: Aphididae

2. Pest description

• Apterous adults: Oval body, reddish‑brown; covered by abundant white waxy secretion, with a woolly appearance; very reduced siphunculi; short cauda.
• Winged adults: Darkened head and thorax; transparent wings; reddish‑brown body with a smaller amount of wax; wing venation typical of the genus Eriosoma.
• Nymphs: Similar to apterous adults, but smaller and with less dense waxy secretion.

3. Main hosts

• Main host: Apple tree.
• Occasional secondary hosts: Species of Crataegus (hawthorn) and Pyrus spp..

4. Symptoms and damage

• Formation of white woolly masses on branches, trunk, roots and pruning wounds.
• Curling and deformation of young tissues.
• Formation of galls and necroses at feeding sites.
• Reduction of vegetative vigour and growth delay.
• Excretion of honeydew, favouring the development of sooty mould.
• Potential to compromise wound healing and increase susceptibility to secondary diseases.

5. Biological cycle

• Species with several annual generations.
• Parthenogenetic reproduction during much of the year.
• Populations develop on branches, trunk and roots, and may persist throughout winter.
• Development favoured by mild climate and high humidity.
• Limited dispersal capacity, but aided by winged forms and by cultural practices.

6. Monitoring

• Direct observation of branches, trunk and pruning wound areas.
• Assessment of the presence of woolly masses and galls at feeding sites.
• Inspection of roots in young or weakened plants.
• Counting of colonies to support decision‑making in integrated protection.

7. Management measures

• Cultural: Removal of heavily infested branches; disinfection of pruning tools; improvement of canopy ventilation; use of tolerant rootstocks when available.
• Biological: Conservation of beneficials such as Aphelinus mali (specific parasitoid), Coccinellidae and Chrysopidae.
• Integrated protection: Intervention only when population levels justify it; preference for selective methods compatible with beneficials.

Bibliographic references

• Blackman, R. L., & Eastop, V. F. (2000). Aphids on the World’s Crops: An Identification and Information Guide. Wiley.
• Blackman, R. L., & Eastop, V. F. (2006). Aphids on the World’s Herbaceous Plants and Shrubs. Wiley.
• van Emden, H. F., & Harrington, R. (2017). Aphids as Crop Pests (2nd ed.). CABI.
• Dixon, A. F. G. (1998). Aphid Ecology: An Optimization Approach. Chapman & Hall.