"These Goldenrod (Solidago sp.) leaf galls are caused by a fly (Cecidomyiidae: Asteromyia carbonifera). These flies also carry a symbiotic fungus (Botryosphaeria dothidea = Sclerotium asteris) with them. The Gall Midges disperse the fungus and the fungus aids in keeping away parasitoids that would attack the developing Gall Midge larvae. In the [top] photo the lower two inserts are the same old gall. The one on the right has had the surface peeled back to expose the black fungus underneath. This wearing off of the upper surface would occur naturally - but I was not that patient so I used my knife to speed the process. When one observes 'tar-spots' on the leaves of Golden Rod it is all that is left of the gall – only the black fungus remains." (R. Orr, pers. comm.)
Asteromyia carbonifera blisters on Conyza canadensis in Baltimore City, Maryland (7/17/2013). Determined by Charley Eiseman/BugGuide.
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Thomas Wilson.
Asteromyia carbonifera in Montgomery Co., Maryland (10/10/2020). (c) Jim Moore (Maryland), some rights reserved (CC BY-NC).
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Jim Moore.
Asteromyia carbonifera in Montgomery Co., Maryland (10/10/2020). (c) Jim Moore (Maryland), some rights reserved (CC BY-NC).
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Jim Moore.
Asteromyia carbonifera in Montgomery Co., Maryland (10/10/2020). (c) Jim Moore (Maryland), some rights reserved (CC BY-NC).
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Media by
Jim Moore.
Asteromyia carbonifera is a species of gall midges in the family Cecidomyiidae.[1][2][3][4] It creates galls on Solidago plants. Females can lay up to 300 eggs at a time and often collect conidia of the fungus Botryosphaeria dothidea, which is deposited on the plant alongside the eggs. The larvae grow within the gall that the fungus creates, a form of mutualism.[5]