December 2005

The winter solstice approaches, there have been several days with sub-zero temperatures, not to mention gales, heavy rainfall and fog, yet ladybirds, especially the 'harlequin' Harmonia axyridis are still out and about! 

	Temperate and northern ladybirds need to become dormant in winter,  partly to avoid inclement weather. Even if they remain active, there will be no food available for them.  However, as these pictures of Chiswick Park (all  © Mick Massie) on 7th December show that there is still much foliage on the trees and therefore, possibly, aphids and other insects for ladybirds to eat.
	Some foliage (left) has the traditional autumnal colouring but some trees, particularly sycamore (right), still bears green leaves.  There are considerable numbers of aphids on some trees - even in Sheffield, which has been considerably colder than London recently.  The late holding of foliage, as well as supporting prey animals, gives some shelter from the elements.
	Willow, Salix, trees (left) are deceptively green - due to flowers rather than leaves. The presence of leaves will aid other ladybirds as well as the 'harlequin' - many of them are mildewed thus providing resources for the mycetophagous orange ladybird, Halyzia sedecimguttata. Indeed, this species too is still active - David Element has seen quite a few in Collier's Wood.
	The Chiswick harlequins are not all on trees. These specimens were exposed on posts in a car park.  Especially on the right-hand picture, it is possible to see the empty bodies of aphids and a light covering of cobweb deposited by the local spiders. Some ladybirds do die in spiders webs but these large, well-armoured ladybirds are not likely to be eaten by tiny spiders such as Theridion species. As elsewhere lately, ladybirds are predominantly of the 19-spotted succinea form.

The late loss of leaf in some species is unusual of itself. Some trees, such as  birch, Betula spp and lime, Tilia spp.,  lost their leaves at the "usual" time and ash, Fraxinus excelsior, deposited its leaves en masse after the first heavy frost.  Oaks, Quercus spp., were late to achieve their autumn colouring and many still retain some leaves, even in South Yorkshire.  The leaves of sycamore seldom actually change to gold or red (unlike other, exotic maples, Acer species.) - this year some of the leaves turned papery with the frost but others are still green and apparently well .... it will be interesting to see what the UK Phenology Network makes of this.  It will also be interesting to see what the large numbers of ladybirds on the trees do when the leaves fall and the weather gets colder.

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CREATED 11/12/05