Spring is Coming!

…he said hopefully, from beneath several feet of snow, as the mercury struggled to rise above 0°F.

Which is to say, the sedge leafminer I collected two months ago decided it was springy enough in my house to complete its metamorphosis and emerge as an adult moth yesterday.


That was how the mine looked on January 1; here is the completed mine after the larva abandoned it on January 16:


By the time I discovered it, the larva had spun loose webbing over the leaf surface and was already looking like a chubby prepupa:

IMG_0034 IMG_0037

Four days later, it shed its skin to reveal a pupa that looked just like a tiny (4 mm) version of the chrysalis of a pierid butterfly (such as a cabbage white)–complete with the little silk “girdle” slung over it.  (Looking at the above photo, you can see that the “girdle” was originally pointed toward the head, but flopped the other way as the skin was shed.)


Exactly a month later–four days ago–I noticed that the pupa was suddenly looking a lot darker.


And yesterday it had become an empty shell…


…and an adult Elachista had emerged.


So my suspicion was correct, and I feel reasonably good about calling this one Elachista cucullata.  In her 1948 revision of the Elachistidae of North America, Annette Braun (who first described this species in 1921) stated that among the Elachista species with known larvae, the larva and pupa of this one are distinct in being red with paler, pinkish mid-dorsal and lateral lines.  (I would have called it pale with two red stripes, but same idea.) Her description of the mine also matches well; in autumn, the larva makes a linear mine from the tip of a sedge leaf downward, then broadens it in the spring.  Whereas this mine was confined to one side of the midrib, she says the mine broadens to occupy the whole leaf–but she also says that the host plants are “several narrow-leaved species of Carex, especially C. jamesii.”  This was a relatively broad-leaved species; I’ll try to remember this summer to go and see exactly which species it was.

Now, of course, Lauri Kaila went and described 85 more North American Elachista species (some of them named after Tolkien characters) after Braun’s revision, and only a tiny number of the 138 named species have known host plants, let alone described immature stages.  But we’ll go with “probably Elachista cucullata” until new information comes to light.

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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4 Responses to Spring is Coming!

  1. Anonymous says:

    great images

  2. Kathie Fiveash says:

    I couldn’t find any of the Tolkien names! Thanks for your wonderful posts. They always remind me of the complex beauty of the smallest things. Well, not the smallest, but you know what I mean. The inconspicuous.

    • I wouldn’t have caught them either if Kaila hadn’t mentioned the source of the names in his species descriptions. I think they are mostly from mythological figures in the Silmarillion. This list includes 12 Elachista species with Tolkien names (some of them may not occur in North America).

  3. Kathie Fiveash says:

    Wow! What a list for a Tolkien lover. Thanks so much, Charlie!

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