Mystery Creature Found Inside a Grape Tendril

Parasitized Concord grape tendrils
Photo by Brad yslvester, copyright 2011, all rights reserved

I have found my first mystery creature living in my yard. For lack of a better term, I’ll call it the grape tendril grub. I have Concord grapes in my yard and I noticed that two of the grape tendrils, located immediately adjacent to one another, had become bulbous at the tip. This is not typical of a grape tendril which is normally tendril-like in every respect, long, narrow, twisting and smooth. These two had tumor-like growths.



Normal Concord grape tendril
Photo by Brad Sylvester
copyright 2011, Do not copy.



Sectioned tendril showing the cavities and one grub
Photo by Brad Sylvester, copyright 2011. Do not copy.

My first thought is that it is either a fungal infection or an insect. Many insects will deposit their eggs inside the soft tissue of plant so that when the eggs hatch, the larva has a ready food supply and has some protection.

Small orange grub-like creature that was hidden inside
 the swollen grape tendril
Photo by Brad Sylvester, copyright 2011. Do not copy.

I examined the plant in the area of the misshapen tendrils and did not see any insect damage other than the expected Japanese beetle skeletonization of the larger leaves. Generally, though if a bug takes the time to lay eggs in or on a particular species of plant, that’s a bad sign for the plant as it almost always indicates that the larva will eat it. I’ll also note that this grape plant earlier had some spider mites which I removed with an application of soapy water.

I removed the two tendrils and cut the largest one open down the center with a very sharp knife. The largest of the two growths was an oval approximately 4mm X 8mm. Slicing lengthwise down the middle as you can see in the photo, uncovered two hollow pocket and resulted in a smear of orange paste on the knife blade. Oops. One of the pockets still had a bit of the orange color showing, but I apparently caught whatever was in the other pocket quite squarely with the blade, pulping it. I cut the other one open more carefully working in from the side so as not to repeat the mistake and discovered a very tiny orange grub-like shape inside the hollow of the smaller growth which was a sphere of approximately 3mm in diameter.

I rummaged around the house for a microscope some slides and some tools to help me handle and view the thing which was less than a millimeter in length and perhaps a third of a millimeter in width. Once I got it on the slide under a 50-75 power microscope lens, Its shape became clearer. It was definitely grub-like and was waving one end around in the air. As best I could count, it had thirteen ring-like segments. No other detail was readily visible, except that it was thickest toward the middle and tapered a little at either end.

The grub was colored orange as I’ve already mentioned, but to be more specific it was a bright yellow-orange like the skin of a pumpkin.

I can’t find this creature in any reference source. If I were to guess I’d say it’s reminiscent of a lady beetle larva, though very small like one of the Stethorus genus. It is possible that it’s in the pupal stage and not a larva at all. If so its appearance and size more closely aligns with Stethorus, but Stethorus would typically lay eggs on the underside of a leaf… Stethorus spp. would feed on spider mites, though.

What’s interesting about this insect is that it seems to change the plant behavior as well. The tendrils grow bulbous and thick with the plant’s own tissue, not just as a result of displacement caused by the insect’s growth. So either the grape plant is reacting in a defensive manner and has some kind of immune response to the presence of the insect inside it, or the grub is releasing some chemical that alters the plants growth. In either case, the result is a thicker, more secure case around the otherwise defenseless insect inside.

In any case, this one has to be filed under Mystery Creatures for now. I know it’s in the Class of Insects, and I suspect it’s in the Order Coleoptera (beetles), but even the Order is uncertain and I can’t get any further on this one at this point. Ideally, I’d find some more and let them proceed until they emerge from the grape tendril and see if they metamorphose into something recognizable.

NOTE: Kim Phillips, from one of my entomology groups on Facebook, suggests the Grape tomato gall (Lasioptera vitis). That seems like a definite possibility or perhaps (Schizomyia impatientis)?
NOTE 2: Got it, read the answer here!

Blooming Bulb has Concord Grapes if you'd like to add some to your yard.