Stem borer ( Diptera: Agromyzidae) in Actaea

Record Details

Record no.:	0012
Feeding guild:	Stem borer
Taxonomy:	Diptera: Agromyzidae: Melanagromyza sp.
Stages observed:	trace, puparium, adult
Hosts in Actaea:	undetermined A. sp. (baneberry)

The larva of this agromyzid tunnels and pupates in the lower stem. I reared an adult from an overwintered puparium. The posterior spiracular plates of the puparium were separated by approximately their own width, and they each possessed a straight horn about half as long as the width of the plate. Large species (puparium length ~4-5mm).

Featured Images

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fat, ovoid, straw-colored puparium is nestled inside a tunnel with rough, browned walls; the exit window nearby at the end of the tunnel is oval and transparent — Image #: 12-01 Puparium in tunnel in stem. Also note exit window in far wall of stem, prepared by larva prior to pupation.

spiracle plates are round and sclerotized and each is perched on a small knobby protrusion from the posterior end of the puparium — Image #: 12-02 Rear view, posterior end of puparium, showing posterior spiracles.

there is a short, triangular horn in the center of each spiracle plate — Image #: 12-03 Posterior spiracles of puparium.

robust black fly with rounded thorax, yellowish-brown wing bases and reddish compound eyes — Image #: 12-04 Reared adult.

Specimen Data for Images

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Coll. as puparium 10/12/21 and photographed same day, adult em. 03/12/22 and photographed on 03/13/22 (01-04).

Page created: November 7, 2023. Last update: February 6, 2026