Viburnum beetle

[aircooled]

Yet again my V. opulus shrubs have been defoliated by disgusting viburnum beetle caterpillars. They're also having a go at the evergreen V.tinus. There are plenty of blue/great tit nests in the garden but the caterpillars must taste as horrible as they look. I hate to use chemical sprays, does anyone have any suggestions?

Oh dear! Your poor viburnums.

The larvae (caterpillars) come out in April, so I think you may be a bit late to do anything about it this year. The worst of the damage will already have been done, and it will be too late to treat. Please don't use a broad-spectrum insecticide as you will inevitably hit all the lovely insects too - butterflies, bees etc. which would be a shame. You might also hit some of the insects that are keeping them in check! The good news is that viburnums are tough buggers and should be fine.

However, there is one thing you can do now, which is to put a nasty sticky barrier under the affected plants. The larvae crawl down the plant about now (I think, others may know better) to pupate in the soil, and this should catch some of them and stop them getting there.

The adults then climb back up the plant in August to lay eggs. So to preserve next year's viburnums, you could spray with a specific insecticide for beetles in August (look for pyrethrum). Then get out there in September and get rid of as many of the eggs as you can by hand (prune if need be).

You can then do an additional spray of pyrethrum next April if you feel that they are still out of control. Hopefully this will start to solve the problem.

Thanks. I might blast the buggers with pyrethrum now, the shrubs are covered in them. I think I've got a tub of fruit tree grease somewhere so will try that too. I used to rub the caterpillars off by hand when the plants were smaller but it would be too big a job now. Might prune them anyway - will encourage some new growth when the pests have gone!