Hormaphis

Osten-Sacken, 1861

witch hazel aphids, palm aphids

Species Guides

Hormaphis hamamelidis(Witch-hazel Cone Gall Aphid)

Hormaphis is a of gall-forming aphids in the Aphididae, containing at least three described distributed mainly in eastern North America. The genus includes the witch hazel cone gall (H. hamamelidis), which induces distinctive cone-shaped galls on witch hazel (Hamamelis virginiana). Species in this genus exhibit complex plant manipulation, including alteration of host phenolic metabolism to create favorable gall environments. The involves a strategy where hatch before host budbreak to ensure gall formation opportunities.

Hormaphis by (c) Ken-ichi Ueda, some rights reserved (CC BY), uploaded by Ken-ichi Ueda. Used under a CC-BY license.

Hormaphis hamamelidis by (c) Carrie Seltzer, some rights reserved (CC BY), uploaded by Carrie Seltzer. Used under a CC-BY license.

Hormaphis hamamelidis by no rights reserved, uploaded by Becky Dill. Used under a CC0 license.

Pronunciation

How to pronounce Hormaphis: /hɔrˈmæfɪs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Images

Habitat

Associated with deciduous forest understory, specifically on plants Hamamelis virginiana (witch hazel) and palms; galls formed on leaves of host plants

Distribution

Eastern North America; records include Vermont and surrounding regions

Seasonality

hatch in early spring before budbreak; gall formation occurs during leaf development; activity tied to host

Diet

Phloem sap from plants Hamamelis virginiana and palms; feeding induces gall formation on host leaves

Host Associations

Hamamelis virginiana - primary witch hazel; induces leaf galls
palms - specific palm not identified in sources

Life Cycle

hatch in early spring, often before budbreak as a conservative strategy. Founding females (fundatrices) induce galls on developing leaves and reproduce within them. Gall development precedes and supports . Later gall formation correlates with higher fundatrix , contrary to typical patterns in temperate forest herbivores.

Behavior

Fundatrices manipulate plant phenolic metabolism, increasing condensed tannins and decreasing hydrolyzable tannins in galls. Gall size correlates with reproductive success; fundatrices actively promote gall growth through physiological manipulation. hatch timing is decoupled from tight synchrony with host budbreak, representing a risk-spreading strategy.

Ecological Role

Gall formation creates localized carbon sinks on plants; altered phenolic chemistry in galls may affect herbivore interactions and decomposition processes