Contarinia

Distinguished from other Cecidomyiidae genera by the combination of: (1) interrupted costal vein after union with R1 or third vein, (2) four-segmented palpi, (3) simple tarsal claws, and (4) male antennal flagellomeres with binodose structure and single circumfilum per node. Similar genera such as Stenodiplosis (now often synonymized or closely related) may require examination of genitalia or larval host associations for definitive separation. Species-level identification typically requires association with host plant and microscopic examination of adult morphology.

Primarily associated with living plant tissues including inflorescences, flower buds, fruits, and meristematic growing points. Some species utilize fungal mycelia growing on plant material. Agricultural habitats are common for pest species, while others occur in natural vegetation. Pupation occurs in soil or within plant tissues.

Worldwide distribution with species documented across North America, Europe, Asia, and other regions. Native ranges vary by species; some are invasive. C. nasturtii is native to Europe and invasive in eastern North America (Ontario, Québec, Prince Edward Island, Nova Scotia, and Minnesota). C. sorghicola occurs in sorghum-growing regions including the southern United States. Climate models predict potential spread of invasive species to additional agricultural regions.

Activity patterns vary by species and climate. In temperate regions, adults emerge in spring when host plants flower. Multiple generations per year are common, with generation times as short as 14-16 days under favorable conditions. Some species enter diapause to overwinter as pupae in soil or plant debris. Late-planted crops often experience higher infestation levels due to population buildup through the season.

Larvae of most species feed on plant tissues, particularly meristematic cells of developing inflorescences, flower buds, or fruits. Some species are fungivorous, feeding on mycelia of fungi such as Choanephora that infect plant inflorescences. Adults of some species feed on fungal mycelia; adult feeding habits of many species are poorly documented.

• Brassica napus - larval hostCanola/oilseed rape; C. nasturtii causes significant damage
• Brassica oleracea - larval hostCole crops including cabbage, broccoli, cauliflower
• Brassica rapa - larval hostTurnip, Chinese cabbage
• Brassica juncea - larval hostMustard greens
• Sinapis alba - larval hostWhite mustard
• Sinapis arvensis - larval hostWild mustard, weed host
• Camelina sativa - larval hostFalse flax; newly documented host for C. nasturtii
• Arabidopsis thaliana - larval hostThale cress; laboratory host for C. nasturtii, novel model system
• Thlaspi arvense - larval hostField pennycress, weed host
• Lepidium densiflorum - larval hostPepperweed; newly documented host for C. nasturtii
• Neslia paniculata - larval hostBall mustard; newly documented host for C. nasturtii
• Diplotaxis muralis - larval hostWall rocket; newly documented host for C. nasturtii
• Erysimum cheiranthoides - larval hostWormseed mustard; newly documented host for C. nasturtii
• Sorghum bicolor - larval hostGrain sorghum; C. sorghicola is major pest
• Sorghum halepense - larval hostJohnsongrass; overwintering host for C. sorghicola
• Citrus - larval hostC. citri attacks citrus flowers
• Pisum sativum - larval hostPea; C. pisi attacks flower buds
• Carya cathayensis - larval hostChinese hickory; C. caryafloralis attacks inflorescences
• Prunus - larval hostStone fruits; C. pruniflorum attacks flower buds
• Artocarpus integer - pollination mutualismTwo Contarinia species feed on Choanephora fungus and pollinate this plant
• Choanephora - fungal food sourcePathogenic fungus on Artocarpus integer inflorescences; food for adults and larvae

Females lay eggs on or near host plant growing points, inflorescences, or buds. Eggs hatch in 2-3 days. Larvae feed for 9-14 days, typically 10+ days, causing tissue damage or gall formation. Mature larvae drop to soil or pupate within plant tissues. Pupation lasts several days to weeks; adults emerge in approximately 2 weeks under favorable conditions, or larvae/pupae may enter diapause to overwinter. Some species complete a generation in 14-16 days, allowing multiple generations per growing season. Adults are short-lived, often surviving only 1-2 days.

Females use olfactory cues to locate host plants for oviposition. Adults are weak fliers and rely on wind currents for dispersal. Some species exhibit diel activity patterns, with peak activity at specific temperatures (e.g., midmorning at 85°F for C. sorghicola). Larval feeding induces gall formation or direct tissue damage; gall formation involves manipulation of plant growth via salivary secretions. Some species engage in pollination mutualisms mediated by fungal food sources.

Major agricultural pests causing yield losses exceeding 50% in some crops. Larval feeding destroys developing seeds, fruits, or meristematic tissues, preventing normal plant development. Some species serve as pollinators in specialized mutualisms with plants and fungi. As gall-formers, they modify plant architecture and may serve as food sources for parasitoids. Weed-feeding species may contribute to biological control of weedy Brassicaceae, though this has not been extensively studied.

Significant economic impact as pests of major crops including sorghum (C. sorghicola), canola and cole crops (C. nasturtii), citrus (C. citri), peas (C. pisi), and stone fruits (C. pruniflorum). Management relies on cultural practices (early planting, uniform flowering, elimination of alternate hosts), scouting, and insecticide applications. Economic injury levels have been developed for some species to guide treatment decisions. Insecticide resistance has been documented in some populations. Quarantine and detection programs exist for invasive species such as C. nasturtii.

• StenodiplosisFormerly treated as distinct genus; C. sorghicola historically placed in Stenodiplosis. Morphological differences subtle, often requiring examination of male genitalia or larval characters. Currently often synonymized with or closely allied to Contarinia.
• DasineuraAnother large genus of Cecidomyiidae with similar gall-forming habits. Distinguished by antennal structure and wing venation details; Dasineura species typically have different palp segmentation and costal vein structure.
• RhopalomyiaGall midge genus with similar life habits. Rhopalomyia species often induce more complex, multi-chambered galls and differ in antennal and genitalic morphology.

• agricultural pest
• gall midge
• Brassicaceae pest
• sorghum pest
• invasive species
• integrated pest management

• BugGuide
• Wikipedia
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Ian Grettenberger Targets a Variety of Pests | Bug Squad
• Bohart Museum Virtual Open House: Think Pests of Alfalfa and Rice | Bug Squad
• Insects that feed on developing grain in the head - AgriLife Extension Entomology
• Super Crop Challenge #13 | Beetles In The Bush
• Investigating the host plant range of Contarinia nasturtii (Diptera: Cecidomyiidae), reveals novel hosts and lack of host plant resistance within a Brassica napus diversity panel.