Western conifer seed-bug

by Richard Jones

[...] it has a distinctive white zig-zag mark across its middle and, with its broad hind legs, it looks as if it's wearing flared trousers.

Western conifer seed-bugA week or so ago I got a call from my parents about some large leaf-bugs they'd found upstairs in one of the bedrooms. From my father's description over the telephone (striking, dark brown, 20mm long, broad and flattened hind tibiae) I had little doubt that it could be anything other than the western conifer seed-bug, Leptoglossus occidentalis. My nephew took the photograph, above, on his mobile, and although it is blurred, there is definitely no mistaking this distinctive and fascinating insect.

This North American bug first arrived in Europe, in Northern Italy, in 1999, and then started to spread out rapidly across the continent, reaching northern France in 2006 and first landfall in the UK, in Dorset, in January 2007. Then, during the autumn of 2008, it appeared all along the south coast, from Portland to Dungeness and in 2009 has started to appear inland, as far north as Cumbria. My parents live in Newhaven, between Brighton and Eastbourne on the Sussex coast, so it was no surprise that they should have turned it up.

The bug's range expansion started long before its Atlantic crossing. Until 1950 it was confined West of the Rockies, but in 1956 had been accidentally transported to Iowa. During the 1980s and 1990s it rapidly colonized the north-eastern USA, arriving in New York in 1990 and Pennsylvania in 1992.

In the USA and Canada it is regarded as a forestry pest because of its damage to conifer seeds and developing cones, especially Douglas fir. Seed destruction rates of 80% have been recorded in some nurseries. It also causes a nuisance by congregating in large numbers in buildings. Early arrivers give off an aggregation pheromone recruiting others to join the throng, until sometimes many thousands are knotted together.

As can be seen from the better photographs elsewhere on the web, the bug is much larger than the common British brown leafbug, Coreus marginatus, which reaches only 15mm, it has a distinctive white zig-zag mark across its middle and, with its broad hind legs, it looks as if it's wearing flared trousers.

Some UK web sites suggest that the Plant Health Department of the Food, Environment Research Agency (part of DEFRA) should be contacted if you find this bug, but it is now too well established to consider any attempts at confinement, quarantine or eradication. They are no longer requesting notification of findings. They have asked me to point out that despite its large size, the bug is harmless to humans; it does not bite or sting and does not spread disease. Like all members of the family, it does give off a slight odour, hence the alternative name of stinkbug. I, however, would be very interested to hear if many people have started to find it.

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Gardeners' World Web User 27/11/2009 at 12:12

Hi Richard, There have been a few reported this year via the iSpot website, so far all from near the south coast: http://www.ispot.org.uk/node/6362 http://www.ispot.org.uk/node/10043 Martin Harvey

Gardeners' World Web User 04/01/2010 at 19:25

jan 2010 I have now found two of these bugs in my house in eastbourne plus one was sees climing the outside wall of the house ithink this is one that came inside

Gardeners' World Web User 12/01/2010 at 12:36

Reply to Julie Thanks for your record. I'm sure we'll be seeing more of this in the next few years. I wonder when it will arrive in London.

Gardeners' World Web User 19/01/2010 at 03:16

I have found many in my house over the past month (4 to 6). I live in New York and not knowing what they where and how harmless they where i killed most of them. After the 4th i googled them and now i know they are harmless! thank you! haha! btw

Gardeners' World Web User 03/02/2010 at 12:21

I found one, upstairs, 1/2/io and still have it captive, here in North Norfolk. It is fascinating, but a baddy, so must it be destroyed??

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