Stem borer (Diptera: Agromyzidae) in Aralia

Record Details

Record no.:	0071
Feeding guild:	Stem borer
Taxonomy:	Diptera: Agromyzidae: Melanagromyza sp.
Stages observed:	trace, puparium, adult
Hosts in Aralia:	A. racemosa (spikenard)

The bright golden puparia of this large agromyzid species may be found in the pith of dead stems of the host in winter or early spring. I reared several adults in spring, along with ichneumonoid parasitoids. Judging by the position of some puparia partly buried within the remains of the stem interior tissue, the larvae probably tunnel in the tissue but could conceivably also graze on the lining of any hollow areas within the stem.

Featured Images

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dry gray stem cracked open showing golden pill-shaped puparium inside — Image #: 71-01 Multiple puparia in the pith of a dead stem of the host in winter.

puparium is cylindrical with rounded ends, yellowish-brown in color — Image #: 71-02 Detail, puparium embedded in pith. Note the shreddings -- a byproduct of the final-instar larva preparing the exit tunnel through which the adult will eventually emerge.

pill-shaped golden puparia with small, hooked paired spiracles on the rear end of each — Image #: 71-03 Several puparia removed from the pith. (larger version)

each spiracle is made of a black disc with a minute protrusion in the middle — Image #: 71-04 Detail, posteriors of several puparia, showing darkened spiracular areas with short horns.

tapered rear end of a single puparium, with the spiracle projecting — Image #: 71-05 Detail of spiracular area on the posterior of a puparium.

black fly with transparent wings, a red eye, and a reddish underside to the abdomen, viewed from the side — Image #: 71-06 Reared adult male, lateral. (larger version)

the small fly is perched on a dry plant stalk with a gray background — Image #: 71-07 Reared adult male, dorsolateral. (larger version)

the fly holds its body a little above the surface of the brown stem it's perched on — Image #: 71-08 Reared adult male, lateral. (larger version)

fly caught in the act of grooming with its rear legs held in the air — Image #: 71-09 Reared adult male, lateral. (larger version)

fly viewed from above with two reddish compound eyes and a red-brown tinge at the base of each wing — Image #: 71-10 Reared adult male, dorsal.

Specimen Data for Images

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Field photo taken 04/19/21 (01); coll. 04/19/21 (02-05); coll. 01/10/22, em. 03/30/22 (06-10, all showing the same individual).

Page created: February 1, 2026. Last update: March 12, 2026