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Photo#1326027
Stem boring beetle, sky blue aster

Stem boring beetle, sky blue aster
Red Oak Prairie, Allamakee County, Iowa, USA
September 1, 2016
Borer in stem of sky blue aster, Aster azureus

The very top of the plant containing this larva had broken off and was blackened - similar to this unidentified sign from the same location, same plant species, earlier in the year:

Remaining stem of living plant had blackening/discoloration at truncated end and an obvious tunnel through it that seemed kind of flattened in cross-section (i.e., tunnel was more oval than round in cross-section). The larva was inside this tunnel, not far from the truncated end/"top" of the stem.

Unfortunately I wounded the larva in the process of opening up the stem and I am afraid it did not survive.

This just looks SO much like a cerambycid...I am not confident enough with my beetle larva ID to be able to distinguish cerambycid larvae with certainty from those of other families of beetles, but I am still going to place it under Cerambycidae for now given the strong resemblance to other long-horned beetle larvae I've seen.

Images of this individual: tag all
Stem boring beetle, sky blue aster Stem boring beetle, sky blue aster Stem boring beetle, sky blue aster

Moved
Moved from Dectes texanus. I haven't been able to find any records of Dectes texanus creating two rows of punctures on a stem like this. The references I consulted all referred to D. texanus ovipositing in petioles (of sunflowers and soybean) and didn't mention rows of punctures that cause girdling or flagging on the main stem. D. texanus does girdle stems, but that is done by late-instar larvae preparing their overwintering chambers at the very base of the stem.

However, two rows of punctures -- with an egg laid between them and a larva that then tunnels downward -- is described for at least one Oberea species. See "Life History and Population Dynamics of Cerambycidae" here.

Moved
Moved from Long-horned Beetles.

I posted this mystery to the Jewel & Longhorned Beetle Forum on Facebook, and Steven Lingafelter and Ted MacRae both said Dectes texanus would be their guess.

Moved
Moved from Beetles.

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