It was a mugging, a gang mugging. 17 culprits – count them – 17 curl grubs munching on the roots of my pelargoniums. These plant muggers can be found everywhere – under lawns, in pots or in garden beds – they're not fussy. They're the larvae of the common black garden beetle and they're very widespread here in Australia.
This is the classic curl grub mugging scenario. Hanging basket with an outside light nearby. You'd think a light would provide some safety, but not from curl grub muggings. In fact, the beetle mum is attracted to the light at night, finds a patch of soil conveniently nearby, and she lays a clutch of eggs. The eggs hatch in the soil and immediately start eating the roots of any plants they find. They're not fussy; they'll eat just about anything. They love lawn grasses, but pelargonium roots will do just fine if that's all that's on offer.
Here's a close-up of the curl grubs. They're usually white and curled up like this. They look like sleeping babies but that's just a front when they feel threatened by bright sunlight. It's OK to handle them with your bare hands, as the hairs aren't nasty, as they can be with some caterpillars.
I dispose of the grubs by tossing them onto the roof of my shed, where the local magpies quickly swoop down for the free feed. In fact, if Aussie readers/gardeners ever see our native magpies standing on a lawn looking a bit odd as they turn their head sideways as if listening to something under the soil, that's exactly what they are doing. They're listening for grubs such as curl grubs munching and moving just beneath the soil.
My pelargoniums were so sad that I bought a punnet of three identical seedlings and planted them into new potting mix, but I trimmed up the best of last-year's plants and planted them in between the seedlings. Hopefully they'll recover and belt along like they did last year.