Everyday invertebrates

Now that autumn is here and a seasonal quietness descends, I go to the window box several times every day to see if I can find any invertebrates.  This has proved quite successful.  Today, for example, I found a walnut orb-web spider, Nuctenea umbratica.

These hide in suitable crevices by day (this one was tucked neatly behind a stipule on one of the sallow wands) and spin their web as dusk falls.  It is one of the few British spiders capable of biting humans, but if it does it only causes a little mild irritation.

Caterpillar variations

The two pebble prominent larvae I brought indoors from the window box sallows the other day are now nearly fully grown and resemble one another rather little.  One is much larger and I would estimate about two and a half times the  size of the other.

It could be that the smaller, paler one (below) will be a male, but I am not sure at which stage sexual differentiation in moths and other invertebrates occurs.  The size of the lower one, by the way, is overestimated by these photos and remember, the head is on the right

More on the pebble prominent

I have discovered a third pebble prominent, Notodonta ziczac, caterpillar feeding on one of the coppiced sallows in the window box.

The head is on the left hand side and the tail on the right is normally raised (or lowered in this case) perhaps to entice predators to attack the wrong end, or not to attack at all.  The caterpillar is still quite small so, if it survives in the window box jungle, there should be more pictures.

The specific name ziczac is said to derive from the German zick-zack (meaning 'zigzag').  It was Latinised to 'ziczac' by Linnaeus when he named the species and is said to refer to the unusual shape of the larva.

A wealth of caterpillars

In the last few weeks I have found the caterpillars of many different species of moth on the sallow coppice in the window box.  The top one in the pictures below is a baby pebble prominent, Notodonta ziczac. Interestingly it seems to have two 'horns' on either side of the head (on the left) which I think are not present in later instars. 

The second picture below is of what I think is a caterpillar of one of the thorn moths.

 

While these caterpillars seem to resemble twigs, they are also very much like bird droppings, especially the pebble prominents which tend to site themselves at the apex of the leaf they are eating.  Inevitably this is said be an imitation that makes them difficult to see,  But if I can find them easily enough, why does it fool the sharp-eyed birds for whom they are a tasty morsel?

There are also two different green caterpillars on the sallow.  I found the top one when it was quite small and it is growing rapidly.  The other is, I think, not going to grow to any great size.

Finally, there is a small caterpillar hiding (not very well) in a kind of silk awning it has sung across one of the larger leaves.

I keep examples of these caterpillars in plastic boxes with supplies of leaves and, usually, they pupate and I have to wait until the moths emerge when they can be photographed and released.

It was Hecatera bicolorata

This morning I rediscovered the small caterpillar I had spotted yesterday on a photograph of smooth hawksbeard (Crepis capillaris).

It is that of a broad-barred white moth (Hecatera bicolorata).

Particularly satisfying to have recorded a new plant in the window box in spring, seen it flower and run to seed, and to have to discovered a caterpillar feeding on it that I also had not recorded before. 

The larvae of this moth is said to feed mainly on hawksbeards and hawkweeds and its position on the stem with its head thrust into a hole to get at the ripening seeds is characteristic.

Smooth hawksbeard performs

The plant of smooth hawksbeard, Crepis capillaris, growing rather uncomfortably on the small rock in the window box produced several flowers earlier this month.

Within a couple of weeks they had run to seed and the 'parachutes' had already departed from one.

As is often the case, when looking through the pictures I noticed a rather fine caterpillar on the plant (see below, lower right).

I went out with a torch to see if I could find it but it had gone.  I found a fine green lacewing though - more of that in a future post.

Phyllody of white clover

Phyllody is the abnormal development of parts of the flowers of various plants as leaves, often with considerable distortion of the bloom.

Some of the white clover, Trifolium pratense, in the window box has developed in this way.

The condition is caused by a mycoplasma, a kind of virus, said to be transmitted by plant hoppers such as Aphrodes bicinctus.

 

I do rather wonder if my earlier discovery of four-leaved and five-leaved clovers in WBX may have been due to this condition.

More on white clover

Having found a four-leaved clover on 29 May, I found a five-leaved clover, also in the window box a few days later.

In the last few years hairy tare has been the dominant non-woody plant in the box, but this year white clover, Trifolium repens, has excelled itself and there is only one rather feeble plant of the tare.

The photos below were taken on 4 July with the clover in full bloom.

A lucky find

The white clover (Trifolium repens) is doing well again this year and, while surveying the plant yesterday, I discovered one four-leaved version.

 

Four-leaved clovers have been an acknowledged bringer of good luck across much of Europe, and now America, for a very long time.  Written references date back almost to the 14th century so it is likely that its powers were acknowledged long before that.

The reason seems to be that the quatrefoil more closely resembles a cross, than the normal trefoil version (on the left of the picture above).  Indeed, many Celtic crosses have four arms arranged in a similar way to the quatrefoil.  Perhaps this is also a reflection of the fact that St Patrick is reputed to have explained the Holy Trinity, the Three in One and One in Three, by reference to the normal three-leaved clover indicating that the four-leaved version also had a special significance.

The four-leaved variant is thought to be caused by genetic or chemical disturbance (what else could it be - physical damage perhaps?)

It is difficult to say how abundant four-leaved clovers are in any particular area.  If people spend time looking for them in areas where clover is common they usually seem to find a few, but part of their mystique obviously derives from their relative scarcity.  So far as the window box is concerned, I have only found this first one ever among the several hundred leaves currently present.

Minim ants

For the last week or so there have been a few small, dark ants running about on the rim of the window box and scrambling about in the sallow coppice.

Through many iterations in different books and web sites they persistently ran down to the very common Lasius niger, variously known as the black ant, the black garden ant, the small black ant etc.

The trouble was all the examples I saw were half to three quarters the size of L. niger, with which I am very familiar from elsewhere in the garden.

An enquiry on the Bees Wasps and Ants Recording Society discussion group quickly produced an undoubtedly correct explanation from Mike Fox.  He wrote "What you are probably looking at here are 'minims'. These are first, or at least early, generation workers from a new colony. It is likely that a new queen of Lasius niger, after mating during last years nuptial flight, has spent the winter in your window box and has, this spring, started a new colony. Her first batch of workers will be much smaller than normal and once the colony becomes properly established normal size workers will be produced."

Apparently it helps a colony to increase more rapidly in size and become firmly established if there are a larger numbers of small workers initially, rather than a smaller number of large ones.

I found these minims enjoyed a drop of golden syrup painted on one of the sallow stalks - makes them easier to photograph too.

Epiphragma emerges

I was studying the window box yesterday evening and noticed a small bump on the top of the sallow log.

I thought this might be a deposit left by a passing bird but, on closer inspection it seemed to be the head of an insect.

The creature continued to grow like toothpaste extruding from a tube.  At first I thought it might be a moth.

Having reached its full extent, it tilted backwards and pulled its long legs out indicating that it was a small cranefly (Limoniidae).

Once its legs were free it removed its rear end from the pupal exuvia and strode delicately across the top of the log .

It proceeded down the side and turned round and hung by its legs to continue the metamorphosis.

When the wings had expanded, the fly could be identified as Epiphragma ocellare, a quite common woodland species known to spend its early stages feeding in various kinds of dead wood.

I took one last picture as the light faded.  The insect was still not fully developed but he had folded his wings into their normal resting position and was beautifully camouflaged against the mossy bark.

This morning he had, of course, gone and I wish him well.  As always when witnessing something like this I remain astonished at the complexity of insect metamorphosis and the way in which it proceeds with such unerring precision.

Buttercup and plastic-fed lichen

Another new record in the shape of a buttercup seedling, almost certainly creeping buttercup Ranunculus repens.

 

While peering at the box today, I noticed some lichen-like discoloration on the curved over edges of the box and, on close examination, concluded that it was indeed lichen that had become integrated (or immersed as I believe the lichenologists say) in the plastic.  The 'plant' was also only evident on the outer, sunlit surface of the plastic. 

I am consulting our county expert on these plants and will report back.

February seedlings

Today I coppiced the sallows.  It is remarkable how vigorously they continue to grow without any fertilizer being added to the soil.

While working I noticed a seedling unfamiliar to me.

I suspect it is ragwort, Senecio jacobaea, though it has some similarity to a primrose.  We will wait and see.

In mid-April last year many seedlings of the same kind came up in one corner of the box.

Only one of these survived (I wonder how they decided) and now that its true leaves have developed it is clearly a bramble, Rubus fruticosus agg..

I shall now have to wait for flower and fruit to discover which microspecies it is.

Smooth hawksbeard arrives

On a New Year inspection of Wbx I noticed a wintergreen rosette of smooth hawksbeard (Crepis capillaris) growing on the mossy rock.

This is a first record for the project and I am a little ashamed that I had not noticed in before, though this species grows very rapidly.  I wonder if it will manage to make it through to flowering in a situation where it might experience severe drought.