The spider with emerald jaws

As well as mystery cocoons, breaking up some old fence panels for firewood dislodged numerous scuttling invertebrates. Plenty of woodlice, barklice and so on, and many small spiders, but also a splendid specimen of Segestria florentina. This is the largest species of the familt Segestriidae in Europe, with females reaching up to 22mm in length (excluding legs and other appendages). The family is distinguished by having 6 eyes arranged in a semi-circle (most spiders have 8) and the first three pairs of legs directed forwards (most have the first two forwards and the other two backwards). Although this species can bite (it's apparently painful, a bit like a bee sting or sharp jab with a pin, but not dangerous to humans), when disturbed, they curl up or flee to find a crevice to hide in - being nocturnal hunters using tunnel-webs with radiating threads. First found in Britain in the 19th century, this is a circum-Mediterranean/continental species that most likely arrived with ships to ports in southern England and has since spread slowly northwards - a likely candidate to increase its range as mean temperatures rise with climate change.

A large female Segestria florentina, characteristically curled up when disturbed during daylight.

This photo shows the first three pairs of legs pointing forwards very clearly. They are generally a fairly uniform black in colour with some faint paler marks such as the median line seen here, although this has been enhanced by the camera flash - to the eye, this was a very dark spider. However, the chelicerae (jaws, bearing the fangs) are an iridescent green. She needed a little gentle persuasion to show these, then was allowed to scuttle away under the shed - we do after all run a spider-friendly household...

The iridescent green chelicerae of S. florentina - the arrangement of eyes is also just about visible. Note that I am not testing her ability to bite.

Multiple cocoon of many mysteries

I'm not often stuck for an identification, at least not for long but while dismantling an old fence panel a few days ago, I did find some things I really couldn't identify, at least maybe not...

Cocoons found attached to an old fence panel

The left-hand one is in some ways the easiest - it's probably a moth, maybe the knot grass (Acronicta rumicis) which I have seen in our garden and which makes long grass-covered cocoons (this one is around 55-60mm long including the grass) - hopefully I'll find out for sure when it emerges as it's now in one of my hatcheries.

The other one is less straightforward. As there's a cigar-shaped cocoon inside it, it is more of a nest than a cocoon as such, and appears to have two concentric 'walls', the inner one thicker and covered in tiny wood fragments.

The 'inner' nest around 18mm long, the cocoon inside is around 8mm long.

The cocoon within the inner nest - whatever was inside has clearly emerged, leaving an open end with a small 'lid'

Next to the cocoon, there's clearly a small black shape, plus in the very top photo, there's material between the two nest walls.

The small black shape turns out to be a dead and shrivelled caterpillar - whatever it was, it bore long hairs/bristles which can still be seen. Length approx. 6mm

From this angle, the true legs can be seen towards the head end (left) curled under the thorax, while the larger, stubby prolegs are more clearly visible in the middle/rear

The relatively simple lens/eye arrangment of the caterpillar

I can't tell what this caterpillar is as it is dry and shrivelled, but the form of the inner nest suggests a puss moth (Cerura vinula) or other member of the family Notodontidae. Mature puss moth larvae are large and spectacular, but the first instar is small and black. However, it doesn't have long bristles, so can't be this species, though other members of the family may be plausible candidates. A different question does arise though - cocoons give rise to adults, not larvae, so what is it doing here? If there were wasp eggs, then one plausible explanation would be that it was brought in immobilised by a solitary wasp as a food source for its own young. However, this is a nest with a cocoon in it, not eggs. Also, there is no evidence of a wasp in the cocoon, but there is the material between the inner and outer nest walls. I am unaware of any wasps where a host caterpillar is entombed by a pupating larva to await its adult emergence, but they are a diverse group  often with complex (and often poorly understood) life-cycles, so I imagine it is possible. Alternatively, the caterpillar was simply caught inside a nest construction and starved.

Spider exuviae (moulted skins) within the outer nest

As seen in the photo above, the material consists mainly of moulted spider skins (exuviae) of differing sizes, sugessting an individual spider grew and moulted several times using the thin outer nest (the red structure top-left is a set of mouthparts, almost as large as the whole skin bottom-right). It seems plausible that the hiding place was a good one and a spider simply used it, building its nest around the tougher one already there. Looking even closer there is more to see.

The thin outer wall and the thck inner wall with wood shavings. Just below where they meet, a small white structure is visible in partial shadow.

Hidden behind the larger structures, what appears to be another, much smaller cocoon. This is now also in a hatchery awaiting whatever emerges.

This looks like an opportunistic cocoon-builder that has just used a handy crevice, but it may be related to the larger nests. I don't know which species are involved, but I hope that the two remaining cocoons remain viable and I'll see which species emerge. You never know, it might shed some light on the mystery nest/larva - and if it does, I will, as ever, post it here.

The widow and the vapourer

While collecting brambles to feed my ever-hungry stick-insects, I noticed a batch of insect eggs on top of a silk mat and tunnel which had knitted two of the leaves together. Of course I had to have a closer look and the eggs were of the vapourer moth Orgyia antiqua, while the tunnel contained a spider which I think is probably one of the Steatoda 'false widows' which are mostly harmless but recently seen in many a tabloid frenzy about deadly spiders - I could probably ID it to species but not without pulling it out of its retreat and I'd rather leave it be as I suspect it found the ready-made moth cocoon to be a handy basis for a web (or maybe it happened the other way around). However the moth eggs do lead onto some interesting biology/ecology.

Vapourer eggs on the female moth's cocoon, under which a spider web/tunnel has been created

Entrance to the spider's retreat - I wonder if the black hairs round the entrance are from a vapourer caterpillar or something else. The flask-shaped moth eggs are clearly visible, including the dark dimple and band at the top.

The spider, probably Steatoda sp. is just visible within

Female vapourers are wingless and do not disperse as adults. Instead when they emerge from their pupal cocoon, they emit pheromones to attract the winged males (they are highly active flying zig-zag routes during the day, and sometimes at night, to find females) and once mated lay their eggs on their old cocoon. The larvae, which feed on various trees and shrubs, are highly distinctive with tufts of yellowish hairs on their dorsal surface and longer, narrower tufts at both ends. The adults are less spectacular and images of them can be seen on the excellent UKMoths site here.

Vapourer moth larva

Vapourer moth larva

Vapourer moth larva

No clouds, no rain, no cold, November

This title of this post may well be inaccurate by tomorrow, but for now - in this part of Britain at least - it is warm, dry and sunny. More importantly, it has remained warm apart from a couple of cold nights and dry apart from a few days of stormy rain for much of the autumn. This of course affects our wildlife. For example, a 'proper' hot, dry summer after several cool, wet ones has seen butterfly populations bounce back to some extent, and this is likely to be helped by a long warm autumn. Undoubtedly, migratory birds will have done better than in previous years, being able to find more food for there long autumn flight, and hibernating species will have a better chance of storing enough energy for the winter. Personal observations also bear this out - garden birds are not using our feeders so much as they have been (though I have seen plenty of birds around) - presumably there is still plenty of wild food available.

This year our strawberry plants have fruited into November - some wild plants will be doing the same

A long season of favourable conditions means that breeding/reproduction can go on for longer with 'extra' broods possibly being squeezed in before winter. I have seen late jackdaw broods in chimney-pots nearby, but on a smaller scale, the female Steatoda nobilis false widow spider (one of the species associated with tabloids' recent scaremongering) that lives in our garden storage box has another brood which she guards closely.

Female Steatoda nobilis guarding her egg-sac - two old sacs remain showing that this is the third brood in this sheltered location.

 Of course, it is autumn - leaves are turning yellow and falling - and it has been damp recently, so Fungi are also appearing to remind us that this is not simply an extension of summer. There are 'toadstool' or mushroom-types of Fungi, but personally I am drawn to the smaller species (as I am with invertebrates), some of which have appeared, almost overnight, on some of our garden woodwork...

 

The common species Coral Spot Nectria cinnabarina - associated with dead wood, here it is on a batten forming part of a garden shed

A small species on hardwood garden shelving - I haven't yet identified it but it look a little like an oysterling (Crepidotus sp.)

So, just a few observations about this autumn, but they do give a flavour of how the current and recent conditions affect the wildlife we see - hope you enjoy whatever you are watching out for!