One of nature's lesser wonders
There are some natural parts of the ecosystem that just don’t do it for me – I know that it all works together, balanced and harmonious, but why do we have to have curl grubs? Not only do these pestiferous beetle larvae harm our plants, but they’re ugly as well.
The name ‘curl grubs’ is not strictly accurate. That name belongs to a European pest, also a beetle larva and similar, though smaller. Our curl grubs are the larvae of scarab beetles, cockchafers and Christmas beetles. They are active for all but the coldest month or two, chewing away at the living roots of plants.
Lawns sometimes show dead patches that can’t be accounted for by the family dog. These are usually the result of curl grub infestation. You can drench the soil with Confidor, if you want, but just drenching it with water also works – the grubs come up to the surface to avoid drowning. This is one reason you won’t usually see the dead patches in summer – natural rainfall discourages them.
Outdoor pot plants are commonly infested. That is because the grubs enjoy soil or potting mix with lots of decaying bark or wood detritus. Most of us fail to re-pot our plants regularly (yep, me too!), so the mix starts decaying and creates ideal grub environs.
The answer is to empty all your pots and check for ugly white ‘c’ shaped grubs. They are 2 to 4cm long, so they’re easy to spot. Pick them out, or, if the pot is heavily infested, just throw the lot out. Rinse the plant roots in a bucket of water and replant in fresh mix.
Running a bug light in the evenings can also help reduce infestations. If you zap some of the adult beetles before they can lay eggs you’ll get fewer curl grubs.