Bedeguar Galls

The strange object in the upper image, looking like an alien visitor from outer space, is a young bedeguar gall caused by the gall wasp Diplolepis rosae, which lays its eggs in the dog rose host and triggers this proliferation of tissue. When fully grown, like the example in the bottom image, the core of the gall contains up to 60 chambers, each with a wasp grub inside and enclosed in a mass of mossy grown. These galls are just beginning to become conspicuous on rose bushes around here and by late September they’ll reach their full size. As winter progresses all that spectacular mossy red growth withers but the larvae inside continue to feed through the early part of the winter, pupate and hatch in May as adults that lay eggs in unopened leaf buds. A wide range of other organisms take up residence in the gall, alongside the gall causing organism. Some are inquilines – opportunist squatters that take up residence in the gall tissue - while others are parasites that lay their eggs in the Diplolepis rosae larvae. There are even parasites that attack the parasites – hyperparasites – in these complex communities. You can find more information on this gall, the insect that causes it and the ‘hangers-on’ at http://hedgerowmobile.com/Diplolepisrosa.html