Location: upper leaf, lower leaf, between leaf veins
Form: leaf curl
Cells: not applicable
Possible Range:
The gall's range is computed from the range of all hosts that the gall occurs on. In some cases we have evidence that the gall does not occur across the full range of the hosts and we will remove these places from the range. For undescribed species we will show the expected range based on hosts plus where the galls have been observed.
Our ID Notes may contain important tips necessary for distinguishing this gall
from similar galls and/or important information about the taxonomic status of
this gall inducer.
Created Feb 4, 2026 1:47 PM UTC
•
Last updated Feb 4, 2026 1:47 PM UTC
Separation and redescription of Hormaphis hamamelidis (Fitch 1851) and Hormaphis cornu (Shimer 1867) (Homoptera: Aphididae) on witch-hazel in the eastern United States
Alate virginoparae depart from galls in June and migrate to river birch to produce the first aleurodiform generation on the undersides of leaves. Two more aleurodiform generations follow; the last produces sexuparous nymphs. Mature sexuparae depart from leaves of river birch and fly back to witch-hazel in mid-September to early October and deposit sexual nymphs.
Summary: Hormaphis hamamelidis forms small, conical galls usually without basal constriction, is autoecious on witch-hazel, and lives at high elevations in northern regions of the eastern United States. Hormaphis cornu forms larger, conical galls that are usually constricted at the base, is host-alternating between witch-hazel and river birch, and is found at low elevations in the mid-Atlantic and southern regions of the eastern United States.
