Graminoids & Galls

Last week while conducting a natural resource inventory on Swan’s Island, off the coast of Maine, I got to explore a nice big bog. It had no pitcher plants or leatherleaf, which are plants I normally think of as being prominent in a bog community.  Instead it was largely covered with huckleberry, with scattered spruce and tamarack saplings.  Some of the most abundant herbaceous plants were graminoids (grasslike plants).  The whole place was dotted with white tufts of tawny cottongrass (Eriophorum virginicum), some of which are visible in the lower left of the above photo.  Don’t let the name fool you; it’s actually a sedge. A less showy, but equally (if not more) abundant, plant there was white beakrush (Rhynchospora alba).  Don’t let the name fool you; this, too, is actually a sedge. Here and there, there was some Canada rush (Juncus canadensis), which is in fact a rush. Among the Canada rushes were some much larger inflorescences, reminiscent of those of certain sedges, yet these were not sedges: I’m not sure what I would have thought these were, had I not perused Johnson’s List of the Insect Fauna of Nantucket* last fall to learn what gallmakers and leafminers were already known from the islands of Nantucket and Tuckernuck in preparation for surveying for these things there.  In the entry for Livia maculipennis (Liviidae; listed by Johnson under Chermidae) was this note: “The nymphs develop in a gall formed on rush (Juncus).” Curious what a gall on a rush would look like, I had investigated a bit and found this paper**, which illustrates the gall in which this psyllid develops.  (A psyllid is a member of the superfamily Psylloidea.  Psyllids are sometimes called “jumping plant lice,” “plant lice” being an old name for aphids.)  The structures I found in Maine seemed like a good match, so I broke off a chunk of one and pried open one of the florets, and sure enough I found a psyllid nymph inside:

I took that chunk of the gall home with me to get those photos, so I figured I might as well hang onto it to see if I got any adults.  Sure enough, a few days later there were three adults crawling around in the vial, along with two nymphs.

I haven’t looked for a description or illustration of L. maculipennis, but given that “maculipennis” means “spotted wing,” it seems reasonable that it would look like this.

If you have an eye for tiny things, you may have noticed that there are several psyllids visible in my photo of the gall.  I sure didn’t notice them at the time; I was in a hurry since I had to finish inventorying a whole ~80-acre property in time to catch the ferry back to Bass Harbor.  These psyllids have clear wings and plain orange bodies.  I suspect that they are the same species and are just teneral–that is, they haven’t developed their adult coloration because they have just recently climbed out of their nymphal skins.

Added 6/14/2015: In the comments below, Chris Mallory pointed out that the species I’ve illustrated here is in fact Livia bifasciata, which has been confused with L. maculipennis in older literature. The true L. maculipennis feeds on Juncus acuminatus rather than J. canadensis***.

* Johnson, Charles Williston. 1930. A List of the Insect Fauna of Nantucket, Massachusetts. Publications of the Nantucket Maria Mitchell Association Vol III, No. 2.

** Patch, Edith M. 1916. A Psyllid Gall on Juncus (Livia Maculipennis Fitch). Psyche 23(1):21-22.

*** Hodkinson I. D. & Bird J. 2000. Sedge and rush-feeding psyllids of the subfamily
Liviinae (Insecta: Hemiptera: Psylloidea): a review. Zoological Journal of the Linnean Society 128(1):1-49.

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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8 Responses to Graminoids & Galls

  1. Judy Semroc says:

    Hi Charley – I was wondering if you knew the species of Juncus on which you found the galls (psyllids)? I always enjoy all your posts, and especially liked the historical literature search you did with this one. Hats off as always, Judy Semroc


    • Hi Judy — I realized as I was re-reading this today that I hadn’t been entirely explicit. The galls were modified inflorescences of the J. canadensis, which is why I found them mixed in with the regular J. canadensis.

  2. Marc Lapin says:

    Charley, I have seen these structures many many times and never knew that they were insect-caused galls, let alone the critter that was causing them. It is a common phenomenon. Thanks for so beautifully and quickly teaching us about the psyllids and Juncus galls.
    Marc Lapin

  3. Hi Charley – in doing some research in my review of the genus Livia for BugGuide I came across your wonderful images. While these are very similar to L. maculipennis, after reviewing Hodkinson and Bird’s recent review of the genus it appears that these are actually L. bifasciata. which differs in the broader transverse band on the forewing, a more elongate head and second antenna segment, and wing veins not as strongly arched. The host is Juncus canadensis. Again, fantastic find and photos of this insect, these represent the first live photos I have seen (and the entirely life cycle, at that!)

  4. Steve Young says:

    Hi Charley,
    I have seen these growths on Juncus canadensis but when I cut into them there is no larvae in the middle like a true gall. There are only overlapping leaves. Do you think the Livia is using the protection of the overlapping leaves AFTER they are formed by another process? In that case they would not be a true gall. Everyone cites the 1916 article for the fact that they are galls but this might not be the case. Maybe I am not cutting into the right place to see the larvae.

    • Hi Steve,
      Are you saying there were no psyllids present at all, or just no central cell? Psyllids don’t have larvae, just nymphs, and I don’t believe these galls have a central cell the way many wasp and midge galls do. As you say, the nymphs just live between the overlapping leaves. That doesn’t mean these aren’t true galls; a gall is simply a plant deformity caused by another organism. There are many examples of midge galls without a central cell, and some where the larva simply lives exposed on the surface. In general, mite, aphid, and psyllid galls are relatively simple structures without a central cell. This doesn’t mean these insects/mites aren’t what caused the deformities.

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