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The only saproxylic noctuid moth
Posted by Graeme Lyons , Thursday, 10 June 2010 14:59
We have recently started to appreciate Eridge Rocks has more than just an exceptional sandstone epiphytic flora, it's actually got quite a good saproxylic fauna associated with some big old trees. One fallen Beech in particular is just at the right stage of decay to be crawling with inverts and when I am in the area I have been having a look as I think we would benefit from knowing more about these fascinating insects. I added six saproxylic beetles to the list including Ampedus balteatus (bottom photo), a fairly common black and red click in an old birch stump. I also saw Black-headed Cardinal Beetle and Alice found Tillus elongatus there a few days ago. I also spotted this Rhagium mordax, again common, but a fine looking longhorn beetle. As I was looking at this I noticed some strange 'hammocks' hanging from the underside of the fallen tree (second photo). The hammocks were tied by a thread of silk at both ends. They were covered in what looked like frass from some other saproxylic species, the frass being quite large and sawdust like. One was damaged and a caterpillar was exposed. I pulled open the case and inside was this larvae (top photo), I recognised it as the nationally scarce (Nb) Waved Black! It's covered in yellow warts and long, wispy hairs. The larvae feed only on bracket fungi and are therefore considered saproxylic. We have now found five nationally scarce saproxylic moths and beetles on the same fallen tree! I think next year I would like to put up some traps as there are some really nice red rotten oaks there too. It goes to show that working one tree at the right stage can really pay off. This work will feed back into the management of the site
On the way back to the car I found a single White-legged Damselfly, which was nice.
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