Saturday, 14 January 2006

Looking for wintering bugs

The other morning seemed suitably inviting to get out and about in search of overwintering bugs. Insects can seem a bit thin on the ground during the winter months but, if you know where to look, there are plenty to be found. I made my way to one of my favourite patches, armed with a stout stick, a pooter and a large white net. A pooter is a rather ingenious bit of kit that can best be described as a mini-hoover, with which you can suck up small insects into an observation pot. I started by working my way along the edge of a reedbed, stopping every few feet to position the net low down and to then tap the vegetation above the net with the stick. A fairly firm tap is usually sufficient to dislodge any insects and spiders that have chosen to overwinter in the vegetation. The white of the net enables you to spot those insects that are dislodged as they crawl around amid the bits of plant material that have also been dislodged. Within ten minutes or so I had several dozen individuals crawling around in the net: at least three different species of spider, two species of beetle, a caterpillar and various heteropteran bugs. Many of these were very small – one of the beetles was about the size of a pinhead – and most would need to be examined back at home under the binocular microscope before I would know what they were.

One of the spiders was familiar to me. Its elongated body and the way in which it held its legs – two pairs of legs fully extended forwards of the body and the other two pairs fully extended backwards – made it look like a fragment of grass stem. This was one of the two species of Tibellus spider known from the county. The pale straw colouration of these spiders helps them to perch inconspicuously on dried vegetation and ambush passing insects. Identification of this spider would definitely need a microscope, so subtle are the differences between the two species.

One species that would not need to be taken home for identification was a brownish-green bug, which had dropped into the net as I tapped a gorse bush. This was the aptly named gorse shieldbug, readily identifiable by its appearance and by the forward-pointing spine on its underside. As you might expect, it derives its name from an association with gorse and from the modified wings covering its back that give the appearance of a shield. Overwintering adults are brown in colour but come summer they turn a beautiful yellow-green. It had been a worthwhile visit, with a few more species to add to the list of those recorded from the site.

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