Monthly Mystery #15: Crawl Space Creatures

You’ll have to follow this link to see this month’s mystery objects, since I emailed the photographer for permission to re-post the photos and he hasn’t responded.  His caption reads: “These mounds are in the crawl space of a house. They are very brittle. The openings are about the size of a pencil. The mounds are 3 to 6 inches tall. What made these mounds?”  If I didn’t know the context or the size of the openings, I would have said this was an unusually dense group of crayfish chimneys.  Take a look at the comments below the photo for other possibilities that have been suggested, and also check out the second photo, which shows a whole subterranean city of these things.  These were found in Missouri.   Anyone know what they are?

In other news, the mystery desert legume from two posts ago has been identified as rosary babybonnets, Coursetia glandulosa.  This is not a known host for any leafminer.  Luckily, I have about 20 specimens, which should be sufficient to describe the species… they can get in line behind the 100+ other undescribed North American gracillariid species that Don Davis knows about but hasn’t gotten to yet.

About Charley Eiseman

I am a freelance naturalist, endlessly fascinated by the interconnections of all the living and nonliving things around me. I am the lead author of Tracks & Sign of Insects and Other Invertebrates (Stackpole Books, 2010), and continue to collect photographs and information on this subject. These days I am especially drawn to galls, leaf mines, and other plant-insect interactions.
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10 Responses to Monthly Mystery #15: Crawl Space Creatures

  1. Katie (Nature ID) says:

    Creepy! Curious for an answer…

  2. What about cicadas? We had our 13-year emergence in 2011, and it was quite intense depending on where you lived (I’m in the St. Louis area). If that house is less than 13 years old and is built in a forested (or formerly so) area, I can see this happening.

    If the house is older than that, this could be evidence of 1998, when the 17 and 13-year cycles coincided. Now *that* was a cicada emergence!

    • Yes, my initial comment on the BugGuide photo was:
      “They look an awful lot like crayfish ‘chimneys,’ though pencil-sized openings sound a bit small. I can’t imagine what else they would be. Periodical cicada nymphs apparently sometimes make turrets like this, but I wouldn’t expect them to move horizontally underground and end up emerging en masse under a house… was the house built in the past 17 years?”
      Periodical cicadas do seem to be the most plausible explanation. I’ve experienced two emergences, and never saw any substantial turrets, but I have seen an illustration of a 6″ tall periodical cicada turret in an old book. Have you seen turrets comparable to these in Missouri?

  3. Charley:
    I think they belong to digger bees. They are similar to what I have posted here:
    Differences could be because of differences in soil. Bees emerge (in Iowa) for about a month in the beginning of July.
    Not 100% sure, but they do look like them.

    • The thought crossed my mind, and someone else suggested it on BugGuide, but these are much larger than anything I have ever heard of bees doing. I haven’t completely ruled bees out as a possibility, but whether bees, cicadas, or something else, it seems odd that the homeowner never noticed all these insects coming and going.

      Your observation of what seems to be Anthophora abrupta under your porch is interesting–as I understand it, that species normally nests on exposed, vertical substrates, as I wrote about here. Have you posted pics to BugGuide for John Ascher’s opinion?

      • I did post it to the genus on bugguide and suggested it might be abrupta. I never got a confirmation.
        I also found a single cuckoo bee (Xeromelecta sp.) and swarms of mating cuckoo wasps (Elampus sp.) Since the wasps form a huge mating swarm about three feet from the porch with the digger bees, I think they are associated with the A. abrupta nests. I have seen a wasp corpse in the debris near the nest but have no other proof. The wasps emerge about two weeks prior to the digger bees.
        Check out the cuckoo wasps here:

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