Predators

Synopsis

Record no.:	9008
Feeding guild:	Misc
Taxonomy:	Predators
Stages observed:	trace, egg, larva, pupa, adult
Distribution observed:	IA, WI
Hosts in Unassigned:	various plants

This page collects some of my images of damage to plant stems and stemlike structures wrought by predators searching for endophagous insects. Click the image thumbnail for a larger version. (References referred to in the text below: McCollum 2016; Mapes et al. 2024).

Image Gallery

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Birds hunting Pristerognatha agilana in Impatiens (0287)

Image #: 1-01 Holes made by a bird hunting *Pristerognatha agilana* larvae (0287) in a dead stem of jewelweed.

Image #: 1-02 Collection of raided jewelweed stems.

Image #: 1-04 Detail, collection of raided stems.

Image #: 1-05 Holes made by a bird in a jewelweed stem.

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Birds hunting Endothenia cf. hebesana in Scrophularia (0499)

Image #: 2-01 Lower stem with holes pecked by birds in search of *Endothenia* cf. *hebesana* (0499).

Image #: 2-02 Stem with numerous holes pecked by birds.

Image #: 2-03 Stem with a single entrance hole made by an *Endothenia* cf. *hebesana* larva and seven additional holes made by a bird hunting the larvae.

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Vertebrates hunting Depressaria radiella in Heracleum (0275)

Image #: 3-01 Collection of cow parsnip stems raided by vertebrate predators seeking *Depressaria radiella* larvae or pupae (0275).

Image #: 3-02 Detail, collection of raided cow parsnip stems.

Image #: 3-03 Cow parsnip stem with holes pecked by birds.

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Birds (and small mammals?) hunting Aulacidea gall wasps in Lactuca (0292)

Image #: 6-02 *Lactuca* cf. *biennis* stem so completely dismantled by vertebrates seeking *Aulacidea* larvae (0292) that the stem has lodged.

Image #: 6-03 *Aulacidea* larval cells raided by a vertebrate predator.

Image #: 6-04 More predator damage to *Lactuca* stems inhabited by *Aulacidea* larvae.

Image #: 6-05 Diagram showing bird bill marks interspersed with *Aulacidea* larval cells.

Image #: 6-06 Bird bill marks interspersed with *Aulacidea* larval cells.

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Vertebrates hunting Eurosta solidaginis in Solidago (0514).

Most of the time, when I see Eurosta solidaginis galls that have been raided by a vertebrate, the culprit was a downy woodpecker or black-capped chickadee (e.g., image 7-02). However, in March and April 2013, I came across a population of galls in an old field in southwestern Minnesota that appeared to have been chewed or broken open by a mammal (images 7-04 through 7-12). I have never witnessed this again. For another interesting kind of damage to a Eurosta solidaginis gall, see image 4-04 (Miscellaneous damage to galls and other homes of local feeders, below).

Image #: 7-01 *Eurosta solidaginis* gall (0514) opened by a vertebrate predator.

Image #: 7-02 Four galls on a single goldenrod stem, all opened by birds.

Image #: 7-03 Predator damage to a gall.

Image #: 7-04 Galls chewed or broken open by an unknown vertebrate.

Image #: 7-05 Fragment of gall with what appear to be tooth marks.

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Miscellaneous damage to galls and other homes of local feeders.

The Eurosta solidaginis gall in image 4-04 has a large, externally-excavated hole stuffed with waxy or resinous material similar to that used by some kinds of bees to construct their nests. I suggest that a bee was responsible for this sign, and that it fits into a larger, documented pattern of bees using Eurosta solidaginis galls as nest sites (see, e.g., McCollum 2016 and Mapes et al. 2024). This may qualify more as a inquilinous than a predatory interaction, depending on whether the tephritid larva survives the gall's occupation by the bee. Aside from the repurposed goldenrod ball gall and the other findings below, I have also witnessed so-called "bump" galls made by a Tetramesa species on Elymus (0208) and a single gall of Astictoneura muhlenbergiae on Muhlenbergia (0340) that appeared to have been broken or chewed open.

Image #: 4-03 *Hybolasioptera elymi* in *Elymus* (0206) raided by unknown predator (small mammal?)

Image #: 4-01 Raided gall of *Dasineura pilosa* on *Laportea* (0305)

Image #: 4-02 *Liposthenes glechomae* gall on *Glechoma* (0258) raided by an unknown predator, perhaps a mammal given that I saw what appeared to be teeth marks on it.

Image #: 4-04 *Eurosta solidaginis* gall on *Solidago* (0514) featuring a large hole filled with unidentified waxy or resinous material, apparently the work of a bee or wasp.

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Miscellaneous predation on borers

Image #: 5-01 *Eutrochium* stem raided by unknown predator.

Image #: 5-02 Bird predation on *Epiblema otiosana* in *Bidens* (0096)

Image #: 5-03 *Sambucus* stem raided by bird seeking larva of Lepidoptera: cf. *Achatodes zeae* (0487)

Image #: 5-04 Detail, *Sambucus* stem raided by bird seeking Lepidoptera: cf. *Achatodes zeae* larva (0487)

Image #: 5-05 *Acer negundo* green twig broken open by bird hunting Tortricidae: *Proteoteras* sp. (0002)

References

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Mapes, C.C., Falkowski, J., Setliff, G.P., Gallagher, K., Ruoss, J.P., Mortensen, L., Hinkle, E., Beard, R. and R. Hilger. 2024. Bees nesting in insect galls and a description of a novel nesting site for Megachile montivaga Cresson, 1878 (Hymenoptera: Megachilidae) in goldenrod ball galls of Solidago altissima L. (Asteraceae). The Pan-Pacific Entomologist 100(4): 384-393.[return to in-text citation]
McCollum, A. 2016. Unknown Solidago/Eurosta gall borer - Megachile. Contributor post at BugGuide.net. Retrieved May 19, 2026 from https://www.bugguide.net/node/view/1181294/bgimage.[return to in-text citation]

Page created: April 19, 2026. Last update: June 5, 2026