Unknown Galls on Elm Leaves

Subject: Eggs
Location: Arlington, Texas
May 24, 2014 9:56 am
I took these pic at a nature preserve in Arlington, Texas on May 23rd. My daughter REALLY wants to know what they are – it was her sharp eagle eye that spotted them. Hope the pics are clear enough. We plan or returning frequently to watch what happens with these eggs. Thank you!
Signature: Mary Sarabia

Elm Leaf Galls
Elm Leaf Galls

Hi Mary,
These are not eggs, but Galls.  Galls are growths on plants, and they may occur on leaves, stems, buds, roots and many places on plants.  Galls may be caused by Gall producing insects including wasps, flies and moths, or they may be caused by other arthropods like Mites, or they may be caused by viruses or injuries.  According to BugGuide:  “Gall insects (and mites) are usually highly specific about what kind of plants they use, and even what part of the plant. To maximize your chances of getting a gall identified, record the plant species (include photos of the leaves, flowers, fruits, etc. if you’re not sure), and if it’s a leaf gall, note the position on the leaf (if it’s not obvious from the photo): upper side or underside; midrib, side vein, or somewhere else. Also note whether or not the gall is detachable, the size of the gall, and anything else distinctive about it that may not be clear in the photo. With oaks in particular, which are hosts for hundreds of kinds of galls, every little detail can help to narrow down the options.”
  It appears that the affected plant in your image is an Elm, and we tried to research Elm Galls, but we could not find an exact match to your Galls.  The University of Minnesota has some examples of Elm Galls, but none look like your example.  Generally, the Galls do not harm the plant.  When Galls are the result of Insects, and Insect Galls do tend to be the most common Galls, it is generally produced in the larval form.  When the egg hatches, the larva releases a substance that causes the Gall to form, and then the larva feeds off the developing Gall.  Oak Galls are the most common and Wasps in the family Cynipidae are the most common Gall producers.

Wow!   Daniel!   Thank you so much for all of the information!   I had,  in fact,  decided that they were galls.   I found photos that appear to be exactly the same,  but they are all on oak leaves.   I plan to hike back out there today.   I will take more pictures with the provided guidelines.   The look-alike galls on the oak leaves were identified as “cynipid wasp” and “callirhytis”.   Would you like me to send further photos?
Thank you so much for your help!
Mary Sarabia

Hi Mary,
The closest visual match we were able to find were also Oak Leaf Galls and the Spiny Rose Gall, and we eliminated them because Gall Wasps are so specific about the host plants.  Any follow up photos that are significantly different than the ones you have submitted can be added to the posting.  Please submit any images of different Galls using a new submission form.

Leave a Comment