Out of danger

by Richard Jones

A fascinating find in the garden late last week - the box bug, Gonocerus acuteangulatus, once regarded as one of the rarest insects in Britain.

Box bug, Gonocerus acuteangulatusA fascinating find in the garden late last week - the box bug, Gonocerus acuteangulatus, once regarded as one of the rarest insects in Britain.

This medium-sized (about 10 mm) brown leafbug is a smaller, slimmer and slightly more elegant relative of the very common brown 'shieldbug' Coreus marginatus. Twenty years ago, Gonocerus was given Red Data Book status 1, 'endangered', because ever since its discovery in the late 19th century it was known only from a few box trees on the precipitous chalk slopes of Box Hill, in Surrey.

Although box, Buxus sempervirens, is widely planted in gardens, Box Hill is one of the few places in Britain (along with Boxted in Kent) where it is thought to be a true native. Gonocerus had been found there, on and off, for about 150 years. It feeds on the fruits, using its stylet mouthparts to suck out the juices, in autumn moving to the berries of yew, which also grows profusely on the chalk downs.

However, during the 1990s Gonocerus was found, first, at Bookham Common, then Ashtead, both just a few kilometres away. These were well-established colonies, not just isolated vagrants.

It then started to turn up in other Surrey localities and has continued to spread. This spread seems to have coincided with a concerted survey of the shieldbugs of the county which was later published by the Surrey Wildlife Trust. The box bug is now known throughout most of that county and has also started to appear in neighbouring Kent, Sussex and Middlesex.

The reason for its genuine increase and spread appears to be a change in its foodplant preference from the very restricted box tree to hawthorn, apple, honeysuckle and others. We've got a rather straggling honeysuckle trying to grow over one of our fences, but this specimen was on Clematis armandii, which at this time of year has some very juicy looking fruits on it.

Despite its changing palate, Gonocerus is unlikely to become a nuisance, just another fascinating facet of wildlife in the garden.

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Gardeners' World Web User 09/01/2008 at 14:52

I dont know whether this is the same bug that is inhabiting my rhubarb plants, but I live in Middlesex and I have many many of these bugs, (only ever seen them on my rhubarb).

They look exactly like these bugs in the photograph. If they aren't these then can someone let me know what they might be and are they or will they do any damage to my plants.

Gardeners' World Web User 29/01/2008 at 13:06

Reply to rhubarb grower

Rhubarb would be an odd choice for this fruit-feeder. They are probably the brown shieldbug, Coreus marginatus, which sits about on leaves sunning itself. I've never heard of them being frequent enough to cause any problems in the garden.

Gardeners' World Web User 23/04/2008 at 10:12

Update: Another box bug, this time sunning itself on the ivy, 10 April 2008.

Gardeners' World Web User 25/04/2008 at 17:50

If i put water on my rhubarb leaves will it act as a pestcide? teresa

Gardeners' World Web User 04/05/2008 at 19:48

I have found Red Larvae in some soil in my garden, anyone help?

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