Tuesday, 2 August 2016

Daventry Town Centre

That towns and cities contain lots of interesting wildlife is well understood. Urban foxes and grey squirrels are frequently seen and bird tables can provide lots of surprises. But there is a plethora of smaller creatures - 'mini-beasts' - also present, and these are generally overlooked until, on occasion, they reach pest proportions or unless a nosey individual (Who can I be thinking of?) deliberately seeks them out.

A glance up into a Sugar Maple near Daventry's Leisure Centre revealed a pair of mating Forest Bugs
Pentatoma rufipes. A common bug of course but I am always pleased to see these handsome and harmless creatures around.

Mating Forest Bugs. Daventry, Northants. 30 July, 2016
The tree itself was of interest. The Sugar Maple, Acer saccharinum, is an attractive tree and people are familiar with the leaf shape from the flag of Canada. The form grown in Daventry is 'Laciniatum', with deeply cut, lacy leaves, but look closely and it will be seen that the leaves are covered in pimple-like excrescences.

Vasates quadripedes on Acer saccharinum. Daventry, 30 July, 2016

These are galls caused by a mite, Vasates quadripedes, and although it may be found on other maples I have only ever seen it on this species. It has only been known in Britain from 2002 but is now widespread, once again raising the question of how these flightless creatures disperse so effectively.

Vasates quadripedes, a closer look.
Daventry, 30 July, 2016
Speaking of excrescences, an oak tree, also no more that a hundred metres from busy shops, sported another cluster of these oddities.

This time the culprit was a cynipid wasp, Andricus quercuscalicis, and its target was the acorn. If an oak is affected it is a fairly safe bet that the tree in question is the English Oak, Quercus robur; our only other native oak, Quercus petraea, is only occasionally attacked. (The hybrid between the two, though frequent in parts of Britain, seems to be uncommon in Northants.)
Knopper Gall, caused by Andricus quercuscalicis.
Daventry, 30 July, 2016
On the oak foliage was a specimen of the Berberis Sawfly, Arge berberidis. This fly was unknown in Britain prior to 2002. It has since become widespread and attained the status of a serious pest, defoliating several species of Berberis (Barberry).
Barberry Sawfly, Arge berberidis.
Daventry, 30 July, 2016

Berberis bush nearby had suffered just that fate, with some 50% of its leaves gone.

Berberis species, largely defoliated by Barberry Sawfly.
Daventry, 30 July, 2016
An ash tree was also under attack, but this time from a far less serious pest. A rather neatly furled leaf betrayed the presence of a caterpillar, to be more precise, that of the Feathered Thorn, Caloptilia cuculipennella.

Folded ash leaflet concealing the caterpillar of the
 Feathered Thorn Moth. Daventry, 30 July, 2016
I teased the small green creature from the leaf for a photograph but it looked so pathetic and vulnerable that I returned it to its abode without troubling my camera. (The truth is I couldn't secure a decent image so I gave up.)

Finally, may I leave minibeasts and put in a word on behalf of the liverworts. Where there are crevices in paving or where the base of a wall is a little damp, there they are likely to be found.

Liverworts are easily overlooked. Daventry, 30 July, 2016
At a casual glance the thallus is no more than a greenish patch of indeterminate shape, but look a little more closely. The species illustrated, and found over much of Daventry, is Marchantia polymorpha. The thallus is covered with little cup-like structures and within them, like eggs in a basket, are the gemmae. Each gemma is a reproductive structure and even a rain drop will splash them out of the cup and allow each to begin an independent existence.

Marchantia polyphylla showing the gemmiferous cups.
Daventry, 30 July, 2016

Some, particularly Lunularia cruciata, are a nuisance in flower pots, but generally they are unobtrusive and have been around for rather a long time. Liverworts were among the first plants to colonise the land and recent research has dated the earliest ones at 472 million years before the present. They deserve our respect.

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