12 April 2011

Wednesday Wiggler ~~ Green Dock (or Sorrel) Beetles (Gastrophysa viridula)

 I've chosen this little green beetle as a Wednesday Wiggler because our garden is currently full of them.

I've been trying to identify and hunt out information on them over the past couple of days so that I can determine if I need to worry about these little bugs eating our veggies.

They're a metallic green in colour, about 4mm long with the females slightly longer at about 7mm. The female also has a swollen black abdomen prior to egg laying during the mating season which lasts from March to October.

She lays clusters of tiny yellow eggs on the underside of dock leaves, laying up to 1,200 eggs in two to four broods a year.

The adult's life span is only a couple of months but they can hibernate over winter.

As their name suggests Green Dock Beetles feed almost exclusively on dock and sorrel but if these are not available to them or are in short supply they will eat from the cabbage family (brassicaceae) as well as the borage, violet and buckwheat families. These choices would not be high on their menu though as their larvae will not fully develop if they feed on these plants.

So it would seem that we have a perfectly good reason for NOT ridding ourselves of all the docks in our garden and may have to forget about growing sorrel.

There does seem to be an alarming amount of eggs but as long as the beetles have a good supply of their favourite leaves (and I can attest that there are plenty spreading their seeds in the fields around us too) in theory we needn't be overly bothered by green dock beetles.

This is a great example of why we should encourage all types of wildlife into our gardens to prevent a build up of any one type of insect. The green dock beetle's natural predators are insectivores (such as birds and frogs) and parasites.

By regularly feeding birds, planting hedges, building ponds and not keeping our gardens overly tidy we can encourage a diverse range of wildlife and create a natural balance.

If you have a smaller suburban garden you may be thinking that's all so very well but not feasible. I suspect however, that the little green beetle may be more rampant in a rural garden due to the abundance of food sources in the countryside.



  1. Thanks for the heads up, we grow lots of sorrel and have never ran into this beetle but if we do I now know what it is.

  2. I think you might be okay Mr H as they appear to be confined to Europe and Siberia.... you never know though!


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