Monday, June 29, 2009

Amazing beetles

My tower of logs at the end of the garden is producing some wonderful insects in this warm weather.

Yesterday there were several rhinoceros beetles (Sinodendron cylindricum) and the rare 'ancient woodland' species Tillus elongatus.

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Tillus larvae prey on woodworm larvae and other smaller beetles.  They are supposed to be largely nocturnal and therefore rarely seen (except in traps like my log tower).  All our current Sussex records appear to be from the western half of the macrocounty .  Only the females have this red and bluish black colouring: the similarly shaped males are wholly black.  Charles Darwin, no less, wondered about this sexual dimension where the female is markedly more showy than the male, but did not appear to reach any conclusion.

I wonder if that is a somewhat anthropocentric speculation.  The brighter colours in the female could be simply to do with some chemical manifestations that happen to show up in these colours and do not signify that one sex is trying to use them to catch the eye of the other.

Monday, June 15, 2009

Yellow vetch (Vicia lutea) inland

Yellow vetch is a rather rare native plant of  coastal shingle and bare open land.  One of its strongholds is the Sussex Coast in places like Eastbourne, Shoreham Harbour and Pagham.  Elsewhere it has been widely recorded as an alien.

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The example above (identity confirmed by Paul Harmes, the East Sussex Flora Recorder) was brought to me from Barcombe by a friend who farms there.  The opened flowers are white rather than yellow, though the unopened buds have a yellowish cast.

Away from the Sussex Coast, the Ouse Valley appears to be a route that the plant is taking inland.  It has been recorded from Friston Forest and from several places in the Lewes area which lies a short distance to the south of Barcombe.  Since its arrival on the farm there it has spread to a second field.  It is described in the Atlas of British Flora as a  "Submediterranean - subatlantic species."  Maybe global warming is helping it spread northwards.

Wednesday, June 03, 2009

Horned treehopper (Centrotus cornutus)

I had my first close encounter with a horned tree hopper the other day.  This small sap sucking homopteran is associated with young oak trees and does not seem to be very common.

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The purpose of the 'horns', if there is one, would seem to be to frighten would be predators off as they do not seem to be a display item.

The pronotum also runs backwards over the top of the body like some alien's armour and might, I suppose, have some protective function.

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I find these complicated forms quite difficult to grasp in evolutionary terms.  If such excrescences are of value, why do so few creatures develop them.  Most homopterans, for example, have neither horns nor a backplate, nor do they appear to be on the way to developing them.

Monday, June 01, 2009

Dock bug orgy

The dock bugs (Coreus marginatus) in our garden seem to have been somewhat carried away by the hot weather.

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