The Bug Geek

Insects. Doing Science. Other awesome, geeky stuff.


A few months back I did a post on a common sight in wintry fields: round galls on the slender stems of goldenrod.   In open areas, goldenrod galls are rarely left undamaged; birds such as woodpeckers and chickadees are quick to locate these highly conspicuous snack dispensers during the colder months. 

On a walk this week I found a large, open, grassy field whose autumn vegetation appeared to have been rapidly and thoroughly flattened, perhaps by strong winds or a sudden blanket of heavy wet snow.  The brown, dry remnants of last year’s growth formed a dense mat on the ground.  Amid the grasses and burst milkweed pods were numerous goldenrod stalks, many of which sported fly galls.   Interestingly, it would appear that their horizontality protected them from the sharp beaks of hungry birds; almost every gall I inspected was intact.   Which meant: it was time for a magic trick.

I picked a stem with a nice pair of galls…my pocket knife came out of hiding…a lichen-covered rock became a cutting board…I carefully slid the blade halfway through the fleshy orb…and pried…


Fly larva!  Only one, though; the occupant of the gall on the left had met its end some time ago, but the one of the right – wiggling vigorously!


8 responses to “Magic!

  1. Morgan Jackson April 30, 2010 at 8:54 AM

    Glad you found one! Next you should try bringing them back to your house/lab and rear them out! The adults should be emerging any week now, and it really is a pretty nice looking fly that emerges!

  2. Steve Willson April 30, 2010 at 11:25 AM

    Definitely collect some galls and let the flies hatch. It’s really a neat little fly.

  3. mthew April 30, 2010 at 4:49 PM

    Great minds think alike, or at least gall-alike!

    • TGIQ May 2, 2010 at 8:36 AM

      Ohh, those are great pics! The cotton-candy gall reminds me of one I found, oh, nearly 10 years ago, it was fuzzy and bright pink! Lost the pictures, though, sadly.

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