Callirhytis seminator
(Harris, 1841)
Wool Sower, Wool Sower Gall Wasp
Callirhytis seminator, commonly known as the wool sower, is a that induces distinctive cotton-like on oak trees. The exhibits a complex alternating involving two different gall , though the alternate gall form remains unidentified. are small, dark approximately 3 mm in length. The species poses no threat to humans or oak tree health.
Pronunciation
How to pronounce Callirhytis seminator: /ˌkælɪˈraɪtɪs sɪˈmɛnətɔr/
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Identification
are distinguished by their small size (~3 mm) and dark coloration among . The is most reliably identified by its distinctive : a round, , cotton ball-like structure attached to white oak, initially white and changing color with age. When opened, the gall contains seed-like structures of hardened material surrounding larval chambers. This gall form differs from other oak galls such as the spongy oak apple galls or horned galls of related species.
Images
Habitat
Associated exclusively with oak (Quercus alba) trees. form on oak branches and leaf bases. Found in eastern North deciduous forests and woodlands where white oak occurs.
Distribution
Eastern North America; documented in northwestern Missouri, Maryland, and throughout the range of oak in the eastern United States.
Seasonality
activity and restricted to spring. formation begins in spring; galls persist and change color as they age.
Diet
feed on nutritive proliferated within the tissue induced by the 's chemical secretions. diet not documented.
Host Associations
- Quercus alba - obligate Exclusive for formation and larval development
Life Cycle
with two distinct : one produces stem galls, the next produces leaf galls. The wool sower gall (cotton-ball form) represents one generation; the alternate gall type remains unknown to science. develop inside galls, pupate within seed-like chambers, and emerge by chewing exit holes. Development completes within the gall while attached to the .
Behavior
Females lay directly into tissue, inducing formation through chemical secretions that alter plant development. do not humans.
Ecological Role
-former that manipulates oak tissue development to create larval . Galls may provide food and shelter for secondary inhabitants including and , though specific associates for this are not documented.
Human Relevance
No economic or medical significance. Does not damage oak trees even at high . Non-stinging. Subject of ecological and entomological interest due to distinctive and unresolved alternating biology.
Similar Taxa
- Callirhytis clavulaAlso forms on oak; distinguished by gall (C. clavula galls are harder and less succulent, lacking the cotton-ball appearance)
- Callirhytis quercuspunctataForms gouty oak ; distinguished by gall structure and location on
- Neuroterus saltatoriusForms jumping oak that detach from leaves; distinguished by gall and
More Details
Unresolved Biology
The alternate of C. seminator remains unidentified, a gap in knowledge common to many with complex .
Gall Structure
The seed-like structures visible when the is opened are hardened material, not actual seeds—this is a common point of confusion.