Insecta, Homoptera, Pemphigidae .
Description, Biology, Life Cycle, Damage, Common Names, Images
- Host plants: in America, the country from which it originates, this aphid has a sexual phase on its primary host, the American elm (Ulmus americana). In Europe, it reproduces exclusively parthenogenetically on apple. It is also to be found on quince but is rarely present on pear.
- Apterous nymphs and females overwinter under bark, in crevices in the trunk of trees, cankers or on roots near the collar. Activity resumes in early spring (March-April) and females begin to reproduce, each producing more than 100 nymphs.
Heavy infestations form dense whitish colonies. Adults and nymphs feed by sucking up sap from ligneous parts or tender shoots but never from leaves (*) .
Alatae appear from July onwards and migrate, thereby forming new colonies on other trees.
- The capacity of this aphid to multiply is very important: 10-12 generations succeed one another until the autumn.
- Probing and the injection of toxic saliva cause blisters and cankers to appear which can reach the size of a walnut and interfere with the circulation of the sap. Affected trees decline and can be attacked by secondary pests.
- Biological control attempts were carried out at the beginning of this century, using the parasite specific to the woolly aphid: Aphelinus mali (Hymenoptera).
HYPPZ on line : Species (scientific name), Pests (common names), Glossary, Crops.