Vine Weevil Grubs
Eggs are laid near plant stems in the summer and they hatch into white, horseshoe shaped grubs which stay in the ground during summer and autumn and winter and only emerge into adults the following year. In the outside world they don’t come out until May but in the southwest or in pots in greenhouses or conservatories they may be starting to surface around now.
Vine Weevil larvae are ugly-looking grubs which feast on plant roots, often completely severing them from the upper stems. You can recognise them by their soft creamy-white body, up to 1.5 cm (half inch) long and their brown heads. They often lie in a sort of “C” shape, and look almost like a very fat short caterpillars.
Vine Weevil Adults
As if this wasn’t bad enough, the adults eat the plant leaves also.
Adult Vine Weevils are black beetles about 8mm long with the front part narrower than the back, so that they look as if they have a long nose, or snout. It is important to look for this because they can be confused with ground beetles, which are a gardener’s friend. If you see pronounced notches around the leaves of your plants, then suspect vine weevil. To see them in numbers you will need to take a torch and go out at night-time into the garden and search among the leaves because they feast at night and hide during the day.
Vine Weevil Treatment
Vine Weevils are best treated with nematodes. We supply packs of microscopic worms (eel worms or nematodes) which are watered into pots or open ground with a watering can or hose, and which kill the vine weevil grubs. The nematodes enter the grub, poisoning it and then feeding off it to increase their numbers. The nematodes are active any time when the soil temperatures are above 5 degrees, but to be effective you need to use them when the grubs are active and vulnerable. We recommend two treatments a year – once during March to end May to catch any grubs which may have overwintered and then a second during August to early November to treat freshly hatched grubs.
During the period from June to August you may still be plagued by the adult beetles. There is not much you can do about these apart from catch them, and stamp on them. At least they can’t fly away. Some gardeners go out at night, and lay out a sheet underneath their most vulnerable shrubs or plants. Then they shake the shrub to tip the beetles onto the sheet, gather up the sheet, and dispose of the beetles. One tip is to sprinkle a thick layer of grit around plants at risk to deter egg-laying adults