Winter 2016-2017 Most Diervilla fruits from the 2016 season have senesced but a few are hanging on and, oh, some have holes in them...damage looks similar to this



from northern Minnesota

08/24/17 I finally visit a local Diervilla patch during fruiting time, and yep, a few fruits have holes in them, though it looks like I might be a bit late to the show. Several collected

08/29/17 Collected fruits with holes dissected. Normal Diervilla fruits are multi-chambered, with several seeds per chamber. Pods with holes seem to each have one chamber, maybe two hollowed out, and many pods are misshapen, but mostly, there's little sign of what might have been responsible. But one or two or those misshapen pods have something very interesting still going on inside -- shown here

I think this is one of those partnerships between a fungus (black spheres, white matter) and an cecidomyiid insect (larvae inside black spheres -- see red arrows). The black spheres are not hollowed-out seeds; Diervilla seeds are larger, less spherical, and lighter in color, with a distinct texturing on the surface.