Aggregation of Fungus Beetle Pupae and Larvae

Location: Mogollon Rim, AZ
July 28, 2011 8:12 am
While camping in Mogollon Rim, AZ in July, we rolled over a log and found these bugs, so the images you’re seeing are upside down. These guys were hardly moving, but there were other slow-moving bugs (the black ones) boring into holes in the log. I’m interested in figuring out what these are and I appreciate your time to help in that effort.
Signature: Jenn

Fungus Beetle Pupae

Hi Jenn,
This is a real puzzle for us,  but we believe we know what you encountered.  These look like the Larvae and Pupae of Lady Beetles, commonly called Lady Bugs.  Here is a photo of the Larvae and Pupae of a Twice Stabbed Lady Beetle from BugGuide, and though the match is not exact, we believe you should be able to note the similarities.  We are going to tag this as a mystery because we cannot figure out why such a large number of Larval Lady Beetles would decide to pupate in such a large aggregation under a log.  That does not seem characteristic of what we would expect.  Perhaps we are wrong and they are not Lady Beetle Larvae and Pupae, but we are relatively certain that they are some other group of Beetles.  We will contact Eric Eaton to see if he can provide an answer.  We also want to continue searching to see if there is any documentation of such an occurrence elsewhere on the internet.  Thank you so much for submitting this puzzling identification request.

Aggregation of Fungus Beetle Larvae and Pupae

Eric Eaton makes a correction
August 1, 2011
The beetle pupae are actually of the fungus beetle Gibbifer californicus.


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