Taxodiomyia cupressiananassa

(Osten Sacken, 1878)

cypress twig gall midge

A gall midge in the Cecidomyiidae that induces distinctive twig galls on cypress trees. The spongy galls are initially snow-white, turning brown with age, and eventually drop from the tree with leaf fall. Larvae pupate within the galls, with emerging later in the season or following spring. The is considered a pest of ornamental and native cypress plantings.

Taxodiomyia cupressiananassa by (c) Katja Schulz, some rights reserved (CC BY). Used under a CC-BY license.

Taxodiomyia cupressiananassa by Eric Hunt. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Taxodiomyia cupressiananassa: /tæksiˌoʊdioʊˈmaɪə kjuˌprɛsiænəˈnæsə/

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

Identification

Galls appear as globular, spongy growths on cypress twigs, often mistaken for cones. Fresh galls are snow-white and soft, becoming rusty-brown and firmer with age. Galls bear numerous small projections, giving them a spiky appearance. The galls are larger and more irregular than true cypress cones. are tiny flies typical of gall midges, with reduced wing venation and long, bead-like .

Images

Habitat

Associated with cypress trees in wetland and riparian settings, including swamps, pond margins, and floodplain forests. The has been observed on planted bald cypress trees north of their native range.

Distribution

Native to southeastern United States; recorded from Missouri, Illinois, and Florida. The occurs wherever its cypress trees are present, including areas where bald cypress has been planted outside its natural range.

Seasonality

Galls are visible on trees from mid-growing season through fall. may emerge from galls still on the tree later in the season. Larvae typically overwinter in fallen galls, with and adult occurring the following spring.

Host Associations

Taxodium distichum - primary bald cypress
Taxodium ascendens - primary pond cypress

Life Cycle

are laid on cypress twigs. Larvae induce gall formation and develop inside the spongy gall tissue. occurs within the gall. Galls drop from the tree with leaf fall in autumn. Larvae overwinter in fallen galls, completing development and emerging as the following spring. Some adults may emerge from galls remaining on the tree later in the same season.

Behavior

Larvae manipulate plant growth through chemical secretions, inducing the formation of specialized gall structures that provide shelter and nutrition. The galls are initially soft and white, hardening and darkening as they age.

Ecological Role

Acts as a gall-forming herbivore on cypress trees. The galls represent a significant sink for plant resources and may affect twig growth. The serves as a food source for and other natural enemies within the gall .

Human Relevance

Considered a pest of ornamental bald cypress and pond cypress in urban plantings and managed landscapes. Gall formation can reduce aesthetic value of trees and potentially impact growth, though economic damage is generally minor. Management options are limited and rarely warranted.

Similar Taxa

Gymnosporangium juniperi-virginianaeProduces similarly colored, spiky galls on Juniperus virginiana (eastern red-cedar), which is in the same Cupressaceae. The rust fungus galls differ in being smaller, harder, and producing gelatinous telial horns in wet conditions, whereas T. cupressiananassa galls are larger, spongy, and lack such structures.