Taxodiomyia cupressi

(Schweinitz, 1822)

Cypress Twig Gall Midge, Cypress Flower Gall Midge

Taxodiomyia cupressi is a gall midge (Diptera: Cecidomyiidae) that induces distinctive twig galls on cypress trees (Taxodium spp.). The forms spongy, globular galls on new growth that are initially snow-white and turn brown with age. It has been documented in central Illinois and Missouri, with observations on cultivated bald cypress outside its native range. The undergoes complete with multiple per year, as larvae within fallen galls.

Taxodiomyia cupressi by (c) Ryan Watson, some rights reserved (CC BY), uploaded by Ryan Watson. Used under a CC-BY license.

Pronunciation

How to pronounce Taxodiomyia cupressi: /tæksəʊdɪˈoʊmiə kjuːˈprɛsaɪ/

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Identification

Galls appear as round, spongy growths on cypress twigs, initially white then aging to rusty-brown with numerous small projections. Galls can be mistaken for cones or fungal galls such as cedar-apple rust. are tiny flies that emerge through circular exit holes. Presence on Taxodium in combination with gall confirms identification.

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Habitat

Associated with cypress stands and plantings, particularly Taxodium distichum (bald cypress) and Taxodium . Found in wetland and riparian settings where cypress occurs naturally, as well as cultivated specimens in ornamental plantings outside native range.

Distribution

Central Illinois, USA; Missouri (Callaway County and other locations); southeastern USA where bald cypress is native. Observed on cultivated trees north of native range.

Seasonality

Galls visible on new growth during growing season. emerge from galls later in season. Maggots overwinter inside fallen galls, pupating and emerging as adults the following spring. Multiple per year reported in central Illinois.

Diet

Larvae feed on cypress (Taxodium) tissue within induced galls. do not feed.

Host Associations

  • Taxodium distichum - bald cypress
  • Taxodium species - cypress

Life Cycle

Complete : , larva, pupa, . Females oviposit on new cypress shoots, initiating gall formation. Larvae develop inside gall tissue, pupate within galls, and adults emerge through exit holes. Multiple per year; overwinters as larvae in fallen galls that drop with leaves.

Behavior

Induces gall formation that disrupts normal shoot elongation, causing swollen, distorted growth. Gall formation is synchronized with . exhibit synchronized .

Ecological Role

Phytophagous gall-former that creates structure within cypress . Acts as minor pest in ornamental settings. Provides enclosed microhabitat for developing larvae.

Human Relevance

Minor pest of ornamental bald cypress and pond cypress plantings. Galls may cause aesthetic concern but typically do not seriously harm established trees. Management may be considered in landscape settings.

Similar Taxa

  • Gymnosporangium juniperi-virginianaeCedar-apple rust fungus produces galls on Juniperus with similar rusty-brown color and spiky appearance; distinguished by (Juniperus vs. Taxodium) and gall texture
  • Taxodium distichum cones cypress cones can resemble galls; galls are spongy and irregular while cones have woody, scaled structure

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Sources and further reading