Monday, May 29, 2023

Finger Gall Inquiliines

We found some of these elm leaf finger galls on a tree beside our deck measuring up to 15 mm long.  With a magnifier I could see that  each had an exit hole. so I cut into a few to see their internal structure.  Under magnification I was surprised to find tiny creatures visible only under magnification, living in the hollowed galls.  These are either inquilines or new inhabitants using the structures that have been deserted by the original occupants.  


This little 1mm critter was inside a gall and I couldn't tell if it was an eriophyid mite that caused the gall or another visitor.  It wiggled its butt but didn't crawl around.

This 3mm beetle had found a home in another finger gall.  You can compare it to the dark stained exit hole on the bottom of the gall.  I always wonder what they might find to eat.

You can see these two 3mm flies were crawling around, not particularly disturbed by having their home cut open.  They never did fly away and were still near the gall an hour later moving around at this Youtube link that I filmed with a Celestron MicroCapture Pro digital microscope.  

There are two takeaway lessons in this:

  1. Looking closely you can find lots of life in small spaces.  To quote Dee Morgan, "Big fleas have little fleas upon their backs to bite them, and little fleas have lesser fleas, and so ad infinitum."
  2. I have way too much time on my hands. 
There is more on elm leaf finger galls at this link.