Pterocallis

Associated with alder trees (Alnus spp.); eggs are laid on twigs, petioles, and leaves, with preferred oviposition sites in bud axils and bark crevices. Upper crown and outer canopy positions are favored for egg-laying.

Europe, Northern America, and New Zealand.

Overwintering as eggs; spring egg hatch synchronized with bud burst, with timing affected by temperature. Multiple summer generations occur annually.

Phloem feeder on alder (Alnus glutinosa).

• Alnus glutinosa - primary hostCommon alder; primary host for Pterocallis alni

Holocyclic with overwintering egg stage. Sexual reproduction produces overwintering eggs laid in autumn; eggs hatch in spring. Six or more successive summer generations occur annually. Oviparae (egg-laying females) produce approximately 6 eggs in field conditions (14 at constant temperature in laboratory).

Oviposition site selection favors upper crown and outer canopy positions. Summer pruning of host trees reduces availability of oviposition sites but does not alter site choice. Oviparae reared on leaf regrowth of summer-pruned trees are smaller and contain fewer eggs than those on mature leaves.

Prey for anthocorid bugs (Anthocoris spp.) and coccinellid beetles. Subject to leaf abscission mortality. Egg mortality is highest on leaves (87%) compared to twigs and petioles (57%).

• aphid
• alder
• phloem feeder
• holocyclic
• temperature-dependent development

• BugGuide
• Wikipedia
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Egg distribution and mortality in the alder aphid, Pterocallis alni
• The roles of temperature and food quality in affecting the performance of the alder aphid, Pterocallis alni