Eriosomatinae

Woolly aphids on Crab Apple bark.

Woolly aphids (subfamily: Eriosomatinae) are sucking insects that live on plant fluids and produce a filamentous waxy white covering which resembles cotton or wool. The adults are winged and move to new locations where they lay egg masses. The nymphs often form large cottony masses on twigs, for protection from predators. They occur throughout the Northern Hemisphere.

Many of the numerous species of woolly aphids have only one host plant species, or alternating generations on two specific hosts. The woolly apple aphid, Eriosoma lanigerum is a widespread pest of fruit trees, feeding principally on apple, but also, pears, hawthorn, ash, alders, elms and oaks.

In flight they have been described as looking like "flying mice", and are given nicknames like "angel flies", "fluff bugs", "fairy flies", and "ash bugs".

Taxonomy

The subfamily Eriosomatinae has recently been placed within the family Aphididae.^[2][3] It was previously placed in family Pemphigidae = Eriosomatidae,^[4] but that taxon is no longer valid.^[5]

Genera

Tribe: Eriosomatini

Aphidounguis - Byrsocryptoides - Colopha - Colophina - Eriosoma - Gharesia - Hemipodaphis - Kaltenbachiella - Paracolopha - Schizoneurata - Schizoneurella - Siciunguis - Tetraneura - Zelkovaphis

Tribe: Fordini

Aloephagus - Aploneura - Asiphonella - Baizongia - Chaetogeoica - Dimelaphis - Forda - Geoica - Geopemphigus - Kaburagia - Melaphis - Nurudea - Paracletus - Rectinasus - Schlechtendalia - Slavum - Smynthurodes - Tramaforda

Tribe: Pemphigini

Ceratopemphigiella - Ceratopemphigus - Clydesmithia - Cornaphis - Diprociphilus - Epipemphigus - Formosaphis - Gootiella - Grylloprociphilus - Mimeuria - Mordwilkoja - Neopemphigus - Neoprociphilus - Pachypappa - Pachypappella - Patchiella - Pemphigus - Prociphilus - Thecabius - Tiliphagus - Uichancoella

Diet

Woolly aphids feed by inserting their needle-like mouthparts into plant tissue to withdraw sap. They are able to feed on leaves, buds, bark, and even the roots of the plant. As a result of feeding on the sap, woolly aphids produce a sticky substance known as honeydew, which can lead to sooty mold on the plant.

Botanical damage

Woolly aphids generally are not much cause for alarm, although they can cause rather unsightly damage to plants, which is particularly a problem for growers of ornamentals. Symptoms caused by their feeding on a plant include twisted and curled leaves, yellowed foliage, poor plant growth, low plant vigor, and branch dieback.

Further minor damage can be caused by the honeydew that woolly aphids secrete, which is difficult to remove. While the honeydew itself doesn't cause too much of a problem, the honeydew can cause sooty mold to grow, which can block some of the sunlight needed for photosynthesis.

Wooly aphids (Eriosomatinae) and other sucking insects are often vectors of transmission for powdery mildew (a white fungus which grows on above ground parts of some plants), and other infectious diseases. Typically wooly aphids in subtemperate climates precede and are an indicator of various plant infections, including powdery mildew. Aphids penetrate plant surfaces where they often reside and provide a host of potential inoculants through physical, digestive or fecal secretions. Aphids are often an indicator of other potential plant problems.

References