Between the rainstorms this past weekend, I was excited to find evidence of complex plant-insect interactions within just a few hundred yards of the lodge. Unfortunately, I didn't get a picture of the precise bush that I spotted, but the multiple protuberances on a few leaves that caught my eye were similar to the one below. (1) I brought them in for closer examination.

 Dave Wagner told me that the strategy with any sort of funny plant growth, where the tissue is being manipulated or at least affected by a foreign agent, is to look for a chamber. Chambers indicate an insect, while lack thereof decidedly says fungus. If it's a insect, he told me, Cecidomyiidae was a likely contender, as this family (in order Diptera, sub-order Nematocera) parasitizes a wide range of plants. The common name is gall midge, and their larvae are orange, red or yellow.

After cracking off the 'tentacle,' a small orange larvae similar to those above (2) was nestled at the bottom; it was indeed a Cecidomyiidae larvae! I coaxed it out with a probe into the field of view. Dave pointed out the dark beak-like mandibles at one end of the body, which are used for chewing and the only evidence of an otherwise indistinguishable head.

Evidence of endophytophagous insects can be found inducing any number of bizarre growths across especially woody host plants, such as the tree I found them on. Many hosts are of great economic importance; the Asian rice gall midge has been considered a major pest since the 1960s, while the Hessian Fly and Orange Wheat Blossom Midge attack both bread wheat and durum wheat. Although the precise mechanism is not known, virulent Cecidomyiidae larvae stimulate differentiation of plant growth above their chamber to the production of amino-acid and sugar rich nutritive tissue (this is the gall we see). The cell growth beneath them is simultaneously inhibited; both of these actions cause stress to the plant, and an antagonistic coevolution pattern has resulted in chemical plant-defense responses in many hosts.(3) 

Here is a photo of an adult laying an egg. (4)

(1) http://moremoth.blogspot.com/2011/10/nail-galls.html

(2) http://www.biolib.cz/en/image/id150000/

(3) Grasses and Gal Midges : Plant Defense and Insect Adaptation

M. O. Harris,J. J. Stuart,M. Mohan,S. Nair,R. J. Lamb,O. Rohfritsch

Annual Review of Entomology, Vol. 48: 549 -577 (Volume publication date January 2003)

(4) http://en.wikipedia.org/wiki/File:Cecidomyiidae_laying_eggs.jpg