A little Beetle with possible world changing abilities.

Whilst on a floral survey this weekend we came across some bright yellow orange eggs laid in clusters on the underside of dock leaves. Also on the dock plants were large numbers of metallic green beetles. All of the pieces of this puzzle were there and a surprising story.

The eggs on the dock were laid by the metallic Dock Beetle.

The Dock Beetle (Gastrophysa viridula) is a small stunning looking metallic green beetle that is common throughout the United Kingdom. It feeds on dock plants (Rumex sp.) and sorrels eating a series of 1 cm holes in the leaves. There is no sexual difference between male female beetles however in the breeding season the females black abdomen beneath the metallic wing cases swells immensely, making it seem almost round in shape.

They breed from March to October producing as many as 6 generations per year but usually 2. Each female will lay over 1000 eggs in clusters of  20-45 eggs on the underside of the leaves of its host plant the Broad Leaved Dock (Rumex obtusifolius). These eggs are cream or yellow when they are laid and turn orange as they mature over 3-6 days.

When they hatch, the larvae that emerge are greenish-grey to dark brown. They undergo 3 growth phases (instars) before dropping to the ground and burrowing into the earth where they pupate for 6-9 days.

Adults will feed on docks and sorrels and can fly to new hunting grounds, they are also able to hibernate and thereby persist in a habitat year on year.

Dock beetles have a special anti-predation response, when threatened the roll up creating a tight tiny ball and roll off the leave to the ground or into the nook created at the node of the leaf intersection.

The dock beetles voracious appetite and specifity to dock make it perfect for biological control particularly in the Beef industry where it can be used to combat climate change! Trials in Ireland have used the introduction of dock beetles on beef pasture to reduce and control the amount of dock in the sward. Dock whilst not actively negative to cattle does out compete and supress clover. Clover is nutrient and protein rich and so contribute significantly to the cows diets it also has the secondary effect of reducing bovine methane emissions. Bovine methane is one of the things that makes beef such a carbon intensive food source and this innocuous beetle could lead the way in lowering the cows carbon footprint.