Mystery solved (Janetiella brevicauda) Grape Tumid Gallmaker

Kim Phillips a member of an entomology group to which I belong on Facebook suggested Grape Tomato Gall minutes after I posted the story of a mystery bug this morning. It seemed a good possibility, but I couldn't confirm it, because internet sources seem conflicted about just what Grape Tomato Gall actually is. Bugguide.net could provide no help at all. The source I orginially checked, Ohio State University, for example, believes it is caused by several species of midges saying that the most common is Lasioptera vitis or a species of the genus Cecidomyia. 

While these seemed close in some respects in others they differed. I went away from it for a while, and then thought some more. Cornell University attributes Grape Tomato Gall to a different species, and remarks that although it used to be thought to be caused as many as five different species, it is now recognized as only Janetiella brevicauda that causes this particular gall and it infects only grapes. Cornell correctly identifies the larva as limbless and orange, as opposed to Ohio State's "pinkish in color."

Scars caused by the entry of Grape Tumid
Gallmaker Larvae (Janetiella brevicauda)
Photo by Brad Sylvester, copyright 2011. Do not copy.

Cornell also mentions that the galls will have a very tiny white scar where the insect burrowed into the shoot or tendril. As it happens, I did notice such scars and even photographed them, though I did not include them with the original post. We've got a match! The mystery creature is certainly Janetiella brevicauda, although a very young one as they can grow from microscopic eggs to 3mm in length while in the gall they create.

Furthermore, Grape Tomato Gall is now more commonly called Grape Tumid Gall so people understand clearly that it affects the grape as a host and not the tomato. Tumid means swollen. The insect is referred to as the Grape Tumid Gallmaker.

Quick facts about Grape Tumid Gallmaker (Janetiella brevicauda):
Range: Northeast United States and Eastern Canada
When is it here: All year round. (see Life Cycle).
Lifespan: From a few months to a little less than one year, depending upon the hatch date of the eggs.
Life Cycle: Adults lay about 200 orange eggs in a mass near young grape shoots. The eggs hatch throughout the summer and the larvae burrow into grape shoots, tendrils or leaves. The gall swells around them and they proceed through several instars before exiting the gall and dropping to the ground to pupate in the soil. If it is still early summer, they'll pupate right away and metamorphosize into adult midges which lay a news set of eggs and die. The adults live only a few days.If it is later in the summer, the larvae will overwinter in the ground and pupate in the spring (early June).
Notes: The Grape Tomato Gallmaker is generally not present in sufficient numbers to cause significant harm to vineyards or individual grape vines. Cornell suggests that if they do become a problem, all that need be done is mound up the soil around the grape before they pupate in the spring and they'll be unable to burrow out; problem solved.