Stem borer (Diptera: Agromyzidae) in Osmorhiza

Record Details

Record no.:	0352
Feeding guild:	Stem borer
Taxonomy:	Diptera: Agromyzidae: Melanagromyza sp.
Stages observed:	trace, puparium, adult
Distribution observed:	IA
Hosts in Osmorhiza:	undetermined O. sp., O. claytonii or O. longistylis (sweet cicely, aniseroot)

The puparium of this borer is formed in the stem; adults emerge in spring. I identified the host to genus only; Osmorhiza claytonii and O. longistylis are the two species in the host genus in the geographic area covered by the survey.

I reared an adult female in 2022 and an adult male in 2024. Both possessed a blue-green iridescence on the abdomen. The 2024 individual shared its stem with a Listronotus weevil (record 0350).

Featured Images

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Image #: 352-01 Puparium in stem. (Photo date: April 24, 2021)

Image #: 352-02 Posterior spiracles of puparium, showing small horns on the spiracular plates.

Image #: 352-05 Spent puparium after adult's successful emergence. This puparium gave rise to an adult female.

Image #: 352-07 Anterior end of puparium after adult's successful emergence.

Image #: 352-08 Posterior end of puparium, showing spiracle with small horn.

Image #: 352-09 Reared adult female. (larger version) (Photo date: April 28, 2022)

Image #: 352-co This *Osmorhiza* stem hosted both a *Melanagromyza* larva and a *Listronotus* larva (Coleoptera: Curculionidae; record 0350). It appears the *Melanagromyza* larva pupated first, and then later the *Listronotus* larva moved the *Melanagromyza* puparium to the back of the *Listronotus* larva's pupation chamber along with the *Listronotus* larva's frass. The weevil larva then pupated in its pupation chamber, and when the adult eclosed it remained in the chamber, as seen here, along with the spent puparium after the adult male *Melanagromyza* (image 352-10) emerged from it.

Image #: 352-11 Puparium from the previous image (352-co), tucked into the frass of a *Listronotus* larva.

Image #: 352-10 Adult male that emerged from the puparium in the previous photos (352-co, 352-11). (larger version) (Photo date: April 10, 2024)

Specimen Data for Images

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Coll. 04/23/21, photos on 04/24/21 (01-02); coll. 04/09/22, adult em. 04/26/22, photos of adult on 04/28/22 (04, 09) and of spent puparium on 01/13/23 (05-08); coll. ~03/23/24, em. 04/08/24 (10).

Page created: December 1, 2023. Last update: March 30, 2026