Life on a Bolete

Time for another installment of my celebration of fungus fauna.  The day after Hurricane Irene came through my woods, I went for a walk to survey the damage.  There was practically none, as it turned out, other than the hickory tree next door that fell onto the hemlock in my yard, although there were lots of little broken twigs on the ground, some bearing strange galls I’d never seen before.  As I was walking past this bolete, which was a bit past its prime, a little purple speck moving across its surface caught my eye.

It was the springtail Ptenothrix marmorata, which as shown in my first fungus post is not an unusual thing to find walking around on a mushroom in these woods.

Ptenothrix marmorata (Dicyrtomidae; 1.8 mm).

Ptenothrix marmorata (Dicyrtomidae; 1.8 mm).

From a standing position, this nearly 2-mm bug was the only animal I could see on the bolete, but kneeling down to get a better look at it I saw some smaller specks moving around, all of which turned out to be springtails.  The largest of these were Entomobrya ligata.  I have found this species before by peeling chunks of bark off of dead trees, and its cousins (E. nivalis) by breaking open the black knot fungus galls on cherry twigs.

Entomobrya ligata (Entomobryidae; 1 mm).

Intermingling with these were even smaller springtails in the genus Ceratophysella.  These relatives of snow fleas (Hypogastrura) sometimes form large, purplish masses on puddles in the winter and early spring.

Ceratophysella (Hypogastruridae; 0.8 mm).

These three springtails represent the three major orders of springtails (Collembola, formerly considered an order of class Insecta, is now recognized as a class of its own). Ptenothrix marmorata, along with the garden springtail (Bourletiella hortensis), belongs to Symphypleona, the globular springtails.  Entomobrya ligata represents order Entomobryomorpha, the elongate-bodied springtails.  Ceratophysella and the snow fleas are in Poduromorpha. The remaining order is Neelipleona, which has just 35 described species worldwide. Just one of these is represented on BugGuide.net so far: Megalothorax minimus, which is only a quarter of a millimeter long.  So maybe it was on that bolete and I just missed it.  I did see a similarly small springtail wander across the frame while I was trying to photograph an E. ligata:

Entomobrya ligata (Entomobryidae; 1 mm) and Sminthurinus quadrimaculatus (Katiannidae; 0.3 mm).

Sminthurinus quadrimaculatus is a tiny globular springtail, and I had seen it once before, when one of the mycologists at the Berkshire BioBlitz called me over to see one he had found wandering around on a polypore he was examining under a microscope.  That one was of the two-spotted form, rather than this four-spotted form that gives the species its name.

Sminthurinus quadrimaculatus (Katiannidae; 0.3 mm).

I was unable to find this one again once I’d taken my lens off of it; otherwise I would have tried for some better shots.  There was a slightly tinier thing that was also invisible to me, but which I stumbled upon a couple of times as I scanned the surface of the bolete through my camera’s viewfinder:

A tiny, stalked egg (0.25 mm) found on the surface of the bolete.

I saw the long stalk on this egg and immediately thought of parasitoid wasps.  I remembered reading about some chalcidoid wasps having stalked eggs, but hadn’t bothered to include this information in my book since I didn’t imagine anyone would ever come across one.  I have since learned that certain ichneumons also have stalked eggs. Since the last wasp I’d seen on a mushroom was a eucoiline figitid, I wondered if they, too, might have stalked eggs.  A quick Google search got me to a paper* about eggs of cynipoid wasps, and sure enough, they do.  (However, see my next post for more thoughts about this egg.)  The hosts of eucoiline figitids include vinegar flies (Drosophilidae) whose larvae develop in fungi, and while I was sitting by this bolete, it was visited by some of the little orange vinegar flies that seem to be on most of the fermenting mushrooms around here.

Vinegar fly (Drosophilidae; ~2.5 mm).

Just before I got up to continue on my walk, another fly alighted on the bolete–a fungus gnat, which was smaller than I realized fungus gnats could be.  Unlike the vinegar flies, it was willing to hold still for a picture (for the photo above, I had to cheat and use a shot of a vinegar fly found on another fermenting bolete later in the week).

A tiny dark-winged fungus gnat (Sciaridae; ~1 mm).

* VÅRDAL, H., G. SAHLÉN and F. RONQUIST. 2003. Morphology and evolution of the cynipoid egg (Hymenoptera). Zoological Journal of the Linnean Society 139:247–260.

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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11 Responses to Life on a Bolete

  1. Great post! Beautiful photos!

  2. Pollinator says:

    I like to see that you are collecting illustrations of fungus fauna. I want to learn more about spore dispersal of fungi. Apparently a great deal of it is done by animals, not by the wind. Considering that many of these mushrooms are mycorrhizal, those spore dispersers may play an important role in ecosystems. And they may have been playing a similar role to pollinators long before there were any flowers or pollinators around.

  3. Heather Pembrook says:

    These posts are a true gift and highlight of the day. Your writing style is wonderful and I feel as if you are having a fascinating conversation with all of us. The photos are a thrill and make me go “Wow!”.

  4. Dana says:

    I have enjoyed your “celebration of fungus fauna”. From here out I’ll be examining mushrooms with my hand lens. Thanks!
    I am particularly fascinated by the stalked parasitoid eggs. Do you know what hosts these wasps are targeting? How are these stalked eggs (or larvae) relocated to the hosts?

    • You’re welcome–glad you’ve enjoyed it! Eucoiline figitids are fly parasitoids, and their hosts include vinegar flies as noted above. However, Matt Buffington, a specialist in these wasps, wrote to me yesterday and said it’s unlikely that that’s what this egg is from, because (as far as is known) eucoilines oviposit directly into their host larvae. This is what most parasitoid wasps do, but because I knew that a few of them lay eggs on vegetation, I thought it was plausible that some could lay eggs on fungi. Among the ones that are known to lay eggs on (or in) vegetation, I’m not sure if any have stalked eggs. They all have bizarre and unlikely ways of getting the larvae to the hosts (described on pp. 4 and 65 of my book, if you have it). I don’t have time to go into that right now, but I will write a follow-up post about them eventually, after I’ve investigated this egg a bit more. I’m going to consider it a mystery for the time being.

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