ID Challenge #3

A straight-up identification challenge – see ID Challenge #2 for a detailed explanation of the rules:

Photograph taken June 27, 2010 in northwestern Missouri.  Good luck!

Copyright © Ted C. MacRae 2011

About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.
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23 Responses to ID Challenge #3

  1. Mark Deering says:

    Syrphid fly Larvae?

  2. John Christensen says:

    Looks like a maggot to me. A very clean maggot in fact. One question, though, are we looking at the head or the tail?

  3. tim eisele says:

    Oh, you have got to be kidding.

    Well, what the heck. Given the juiciness of where it is, I’m going to guess that you cut open a gall to find this one. The most common large galls are the ones that occur on goldenrod, so I’ll guess that you cut open one of the round galls. So, that would make it a gall midge (Diptera), but I know how sneaky you are, so . . .

    I’ll go with this: it is a parasitoid wasp larva (Chalcidoidea), and I’ll further stick my neck out for something in the genus Eurytoma, since they are known parasitoids of goldenrod gall midges, and the color and shape (such as it is) looks about right.

    • Sorry, but I’m not kidding on this one🙂

      You earn a bonus point for positing that I opened a gall to find this one, as that is exactly what I did. I’m also tempted to give you a bonus point for realizing how sneaky I am and not falling for something in the Diptera, but since you alone will earn 2 points for the order Hymenoptera I’m gonna try to keep things fair for the others. So, order Hymenoptera, but not Chalcidoidea – so what then…?
      (The statement about this being photographed in northwest Missouri is a pretty big clue!)

      • tim eisele says:

        Um. Well. I’ve got zero familiarity with Missouri, but wild stabs in the dark have worked so far, so let’s see:

        Gall wasps are evidently family Cynipidae. I thought it might be an oak apple, but the gall structure doesn’t look spongy enough, and the Missouri-specific oak apple gall is later in the season.

        OK, I’ll take a chance on the Rosinweed Stem Wasp, Antistrophus silphii. The gall is big enough and looks like it is solid, and the timing is right. And it is found in Missouri.

        • Good job – both the family Cynipidae and the genus Antistrophus are correct. The species is actually A. lygodesmaepisum rather than A. silphii, but I’ll give you a bonus point for revealing your deductive reasoning regarding time of season, appearance of the gall, etc.

          With your exclusive points for the order and the bonus for suggesting I opened a gall, your total points score is now 8 – I think you’ve won this one!

  4. Ben Coulter says:

    Diptera, Acalyptratae, Agromyzidae. I’m hoping this is a leaf miner fly larva. Shot in the dark, really. I was gonna guess a spittle bug fly larva (Diptera, Acalyptratae, Drosophilidae, Cladochaetini, Cladochaeta) but started second guessing.

  5. Ben Coulter says:

    I’m gonna take the NW Missouri hint to mean that the habitat is prairie. And since it isn’t Chalcidoidea, why not Cynipoidea? I am guessing it is:

    Hymenoptera, Apocrita, Cynipoidea, Cynipidae, Antistrophus silphii.

    This species forms galls on the stems of wholeleaf rosinweed, Silphium integrifolium.

    • Not bad! You’ve got both the family and the genus correct, though the species is A. lygodesmiaepisum rather than A. silphii.

      4 pts total (2 for the family, 2 for the genus).

  6. dragonflywoman says:

    Based on the information provided, I’m guessing order Hemiptera, family Cynipidae. An even further wild stab in the dark: gouty oak gall, Callirhytis quercuspunctata? Total guess as I know VERY little about galls.

    • Cynipidae is the correct family (and worth 2 points). I’ll presume your ascribing it to the order Hemiptera rather than Hymenoptera was just a lapsus calami and, thus, won’t deduct any points🙂.

  7. Dave Hubble says:

    Hmmm… I’m not familiar with US species, but if it isn’t a chalcid, it’s either a sawfly or a cynipid – it looks more like a cynipid, so I’ll take a guess at that – something like Callirhytis?

  8. Andrew says:

    Is it Callirhytis seminator?

  9. JasonC. says:

    Assuming that it isn’t a hyperparasite, this larva might be to be Cynpoidea, family Cynipidae.

  10. JasonC. says:

    Oh, what the hey. Random guess: is it a young Callirhytis clavula?

    Also guessing that this is from the generation earlier in the year, since the gall looks more ‘tender’ than the hard ones that appear in fall. I don’t know if that’s even true or not, this is just me clawing in the mud for points like I do in school🙂 .

    • Good guess, but a young Callirhytis clavula gall would not be so succulant, nor would it exhibit the latex ooze that can be seen in this photo.

      But hey, your reasoning is sound, and I’m always inclined to give bonus points to people who “show their work” and make a reasonable case. A bonus point brings your total up to 3 points (and a spot on the podum).

  11. The challenge is now closed – thanks to all who played. Detailed answer post with official points and standings will be posted soon.

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