Saturday, 21 May 2016

Of this and that...

When out surveying an area for invertebrates my camera is always at the ready. It is not that I am a particularly competent or enthusiastic photographer but it is a way of recalling odd or memorable ...whatever.

For example: a casual glance at a Cherry Laurel shrub yesterday brought a couple of ladybirds to my attention.

Harlequin Ladybirds in copula. Daventry

It might appear that two species of ladybird are mating, but of course it is nothing of the sort. The Harlequin Ladybird, is extremely variable and, although in this instance the male is fundamentally black with spots and the female has a ground colour of brick-red with apparently a dozen or more black markings, they are both Harmonia axyrida. It is an unwelcome but well-established alien - but that is another story.

A little further on and I casually passed my net through a birch tree and out came another pair of mating insects - spring had definitely arrived! Ladybirds are of course beetles and some shieldbugs can have vaguely beetle-like appearance (although there are numerous significant differences).
This was a pair of Parent Bugs, Elasmucha grisea.  Their common name derives from the fact that when danger threatens the tiny offspring will creep under their mother's body until the threat has passed. The mouthparts of bugs are modified to form a sort of drinking straw and Parent Shieldbugs imbibe the sugar-rich phloem from birch or alder trees. (Aphids are also bugs.)

Parent Bugs in cop. Daventry 19.v.2016

It seems  hadn't done with shieldbugs for fifty yards further on I passed a line of tall Lawson's Cypress. I had beaten these before in the hope of finding a Juniper Shieldbug, Cyphostethus tristiatus, but with no success. On this second occasion I was in luck.

Juniper Shieldbug netted from Lawson's Cypress.
Daventry. 19.v.2016

The nymphs of this species feed on the cypress cones.  The notorious 'Leylandii' cypress, being a hybrid, rarely bears cones and is therefore of no interest in this context but the widespread planting of Lawson's Cypress has allowed this shieldbug to spread rapidly in recent years.

Shieldbugs - and indeed most bugs - are good, and in some cases strong, fliers. The same obviously cannot be said of mites. These creatures, being arachnids and thus related to spiders, are wingless.
Eriophyes galls on Common Lime.
Byfield, Northants. 20.v.2016
It is therefore a bit of a puzzle how rapidly they disperse and colonise newly created habitats. These pustules on the hybrid Common Lime, Tilia x europaea, are the work of mites, in this case a species of Eriophyes. The identity of the mite in question cannot  be established on this hybrid other than by an experienced acarologist, which I am not. But whatever the species, how does it disperse from tree to tree?  I have not investigated this problem but suspect that phoresy may be the answer. Phoresy is the act of  'hitching a lift' by clinging on to another organism. In some cases it can be insects, but perhaps in here birds are the unwitting carriers.

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