The witch-hazel cone gall aphid (Hormaphis hamamelidis) is a minuscule insect, a member of the aphid superfamily, whose presence on a witch-hazel plant is easily recognizable by a conical gall structure, green at first, it turns bright red.  This gall, rich in nutrients, provides both food and shelter for the female aphid. The host plant is witchhazel (Hamamelis virginiana). At lower altitudes they have a secondary host: river birch (Betula nigra), but this may be a different species.

At the start of spring, females or stem mothers crawl to leaf buds. As the leaf grows, the aphid injects it with a substance, possibly an enzyme or hormone, that causes that the galls to form around her. Once inside her gall the stem mother reproduces asexually and fills the gall with 50-70 female offspring. The second generation develops wings and disperses, repeating the process. The third generation includes both males and females. Towards the end of summer, the third generation reproduces sexually and lays eggs on the branches of the witch-hazel. The following spring the cycle begins anew. This cycle allows the aphid to increase its population dramatically in a relatively short period of time.
The aphids feed on the nutrients present in the gall. Other common gall forming aphids are the spiny witch-hazel gall aphid and the elm cockscomb gall aphid.

harmful

Hormaphis hamamelidis are considered tree pests because they infest and feed on the leaves and stems of trees, causing damage to the foliage and overall health of the tree.

tree pest

Hormaphis hamamelidis can be considered garden pests because they have the potential to infest and damage plants commonly found in gardens, such as witch hazel (Hamamelis) and other ornamental shrubs, affecting their growth and overall appearance.

garden pest

Hormaphis hamamelidis can be considered crop pests because they have the potential to infest and damage certain crops, such as witch hazel (Hamamelis) and other plants that are commercially cultivated for their medicinal or ornamental value, leading to reduced yields and economic losses for farmers.

crop pest

Hormaphis hamamelidis are considered pests because they infest and feed on trees, garden plants, and crops, causing damage to their foliage, growth, and overall health, leading to economic losses for farmers and impacting the aesthetic value of ornamental plants.

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What is witch-hazel cone gall aphid good for?

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