Wednesday, March 6, 2013

Of all the gall!

I had taken a photo of a gall on Wingstem last September
and sent it to Bug Guide for identification. I didn't get an
immediate response and had forgotten about it so I was 
very pleased to receive a notice about it this week. It is a gall 
made by a midge, Neolasiotera incisa Plakidas -1994.
The really exciting part of this is that John Plakidas sent
the notice, and he also named the tiny midge that 
formed the gall!
He also explained that he had published a paper in 1994
about the two species of Neolasiotera that make their
homes on Wingstem, (Verbesina alternifolia). N. incisa
forms galls on branchlets and N. verbisinae Mohn  
uses the main stem of the plant.

Insect galls are formed by tiny creatures that are herbivores
(plant eaters). Each gall serves as the habitat, shelter, 
and food source for the insects that form it. The larvae or 
the adults inject chemicals  into the stem or other parts 
of the plant causing tissues to swell and form a gall. Larvae
develop in the gall and live there until they become fully
grown, and then they leave.

Other galls that I have found in Wildwood include 
another midge, Schizomomyia eupatoriflorae
on White Snakeroot:


One other midge gall is Polystepha pilulae Beutenmuller-1892
on an Oak leaf :

A wasp forms the Larger Empty Oak Apple gall,
(Amphibolips quercusinanis) which is very plain on the
 outside and has an lovely interior structure (see the 
white spikes on the left side of the photo). I took 
the gall apart when I found it lying on the ground 
so that I could get a good shot of both parts:

Another wasp, Diastrophus nebulosus, makes its home on
Blackberry stems.

Aphids also sometimes form galls such as the Elm Sack
gall, Tetraneura ulmi, that I found on an Elm leaf:

Galls are worth a closer look!

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