Arachnids and Insecta

Continuing from my last blog, I have learned a little more about spiders. I have spent a fascinating couple of weeks photographing and trying to recognise the different types in home and garden.

The first lesson I have had to learn is that spiders are not insects. Spiders have 8 legs (Insecta have six) and their bodes have two segments (rather than three as in Insecta) and they do not have antennae like Insecta.

They are of the Class Arachnida, which includes scorpions, mites and ticks. Arachnids (spiders) take their name from the mythical maidens, Arachne, who challenged the goddess Athena to a weaving contest and were changed into spiders. Spiders have been found in Carboniferous rocks dating back 318 million years.

Researchers are investigating novel uses for spider venom, from an eco-friendly alternative to pesticides to treatments for Alzheimer’s disease, cardiac arrhythmia and strokes. In addition, spider silk has lots of engineering uses, from body armour to optical communications. Spiders help farmers by predating on other insects which could harm the crops. This can reduce the need for pesticides if farmers work with the arachnids.

It may be fear of spiders (arachnophobia) was born out of an era in the Middle Ages, when spiders were blamed for inexplicable epidemics of the time, like the plague. Alternatively, it seems to me a justifiable and rational fear that some spiders can kill humans, and if you can’t distinguish which spider can do that, then it is safer to be afraid of all spiders.

Whilst I know it is unlikely to have any spider which might be a threat to me in my home or garden, I do know non-indigenous insects arrive on our shores through cargo from foreign lands. It is always best to learn about the variety in nature, just as our hunter-gatherer ancestors knew so well what to eat, what to touch and most importantly, what to avoid. Similarly, spiders use their very sophisticated senses of touch and chemoreception (as we smell) and vibratory cues (as we hear) to recognize and choose different types of prey. In the case of web making spiders, the frequency emitted by a trapped fly in a web will be different to that of a bee and that in turn will be different to a moth. Once caught in a web, the spider will use touch and chemoreception to check out whether the prey is dangerous or not, noting how it tries to defend itself. When certain it is no threat the spider will apply its venom to the prey then wrap it in a silky sheath.

Metellina segmentata sp. spiral web (with hole in centre)

Metellina segmentata sp. spiral web (with hole in centre)

Metellina Spiders

Metellina with young on crocosnia

Metellina with young on crocosnia


The Orb Weaver spider type is very common and in my garden the metellina whose habit of stretching out along stems when disturbed, earns them the name of ‘stretch orb-weavers’ in some circles. They make the classic orb webs we see in fields, forests and gardens. They are of the family Araneidae. Their web is shaped in a spiral wheel. This is the time of year (late summer to early Autumn) when they are mating and producing young. I photographed them in my garden and experts have told me they are of the subgroup metellina segmentata sens.str. whose young mature early September.
Male and female metellina wrapping prey

Male and female metellina wrapping prey

Another group, metellina menge, mature earlier in June/July. People who monitor these arachnids require a dissected view under a microscope to be absolutely sure of the identification of these similar looking orb weaver types. To be sure of identifying males a close look at the second to last segment of front legs, from the side, with a lens (or a very accurately focused super-macro) would confirm species.

What they will see is

Stout angled spines, only very short perpendicular hairs => m.segmentata.

Stout angled spines with long perpendicular hairs => m.mengei.

The female is the larger of the two in my photos where two are sharing the web. I was photographing numerous males and females. The metellina vary in colour and ‘fatness’ but the pattern on the abdomen and the shape makes them recognisable. It is the broad white borders which are common in metellina.

For anyone wanting a handy reference when out and about, it would seem most keen spider watchers refer to “Spiders of Britain and Northern Europe” (Collins Field Guide) by Michael J. Roberts (Author)

Harvestmen, Harvest Spiders (Order Opiliones)

Harvestman  on water avens plant

Harvestman on water avens plant

Scientific name: phylum Arthropoda, class Arachnida, order Opiliones. From Latin "Opilio", shepherd. Their common name derives from the fact that most are mature in autumn, at the time of harvesting.

I have been advised that the near spider, Mitopus morio which is a species of harvestman, is caught here in my photograph. It can be found in North America, Europe and Asia. The reason it is not a 'true' spider as it has a different body type – this from http://wiki.britishspiders.org.uk/index.php5?title=Category:Opiliones

Unlike true spiders, the body of a Harvestman consists of a single part rather than two. Many have very long legs and suspend their body low near the ground with their legs bent above them, thus forming a capital 'M' shape with the body at the central V of the M. Long legs allow the animal to span large distances between leaves and twigs as it climbs about vegetation. Not all species are long-legged, certain secretive soil and litter species have much shorter legs. World-wide there are over 3,500 species, of which only a couple of dozen are found in Britain……..

The Harvestmen will clean up dead squashed slugs, bird dropping, jam, fruit and other plant remains, as well as live small invertebrates that they might catch

It has been observed to walk using its first, third, and fourth sets of legs, using the unusually long second pair of legs to feel in front of it and probe its environment.

The long-legged harvestmen may be confused with another group known as the "daddy-long-legs" – the cellar spiders (Pholcidae), which are light-brown spiders with very long legs and small body, commonly found in houses.

Daddy Long-legs Spider, Pholcus phalangioides

Enjoying the sun after heavy rain, a Daddy-long-legs

Enjoying the sun after heavy rain, a Daddy-long-legs

http://wiki.britishspiders.org.uk/index.php5?title=Pholcus_phalangioides

High up where the ceiling meets the wall, fine tangles of web are often the bane of the house-wife. Suspended upside down in these fine silken strands is a long-legged spider, Pholcus phalangioides, the Daddy Long-legs Spider. During the day they remain perfectly still and are usually ignored by people. If disturbed, however, they will rapidly vibrate up and down in the web. They are only found inside buildings, particularly in southern England. At night, males go in search of females. When a female is detected, the male gently vibrates her web and after some time approaches very slowly before attempting to mate.

Pholcus catches any unwary insect that gets caught in the web and quickly trusses it up in a bundle of silk. Pholcus will also feed on other spiders that come in range, including their own kind. Having long legs is an advantage when dealing with potentially dangerous prey because Pholcus can draw threads from her spinnerets and flick them at the intruder from a distance. At the same time, the spider keeps itself well away from any danger. Once they are bound up, Pholcus bites its victim. Females can be seen with their eggs held between their chelicerae (jaws). The spiderlings that hatch stay around their mother’s web. As they grow and moult they move further apart for, should one find another, it will eat its brother or sister.

The Wolf Spider

I managed to snap this female carrying her young on her back. The Wolf spider hunts its prey, jumping on them and devouring them. There are many in my garden.

Wolf spider (hunter) carrying young

Wolf spider (hunter) carrying young

And now, mid September, I am constantly walking into the wispy dragline of spiders, using the wind to launch themselves hundreds of miles, as the windy season gets under way, wild gales due this weekend. See

http://www.livescience.com/4142-spiders-fly-hundreds-miles.html for more details of research on the fascinating world of spiders.

Moths

I photographed two moths on ragwort at the end of August. They were in a secluded spot, rarely trodden by humans, high on the fells.

The Antler Moth (Cerapteryx graminis) is a moth of the family Noctuidae. It is a
common species throughout most of Europe.

Ear and antler moth on ragwort

Ear and antler moth on ragwort

From http://en.wikipedia.org/wiki/Antler_Moth

This species is unusual for a noctuid in that there is marked sexual dimorphism. The male has a wingspan of 27–32 mm but the female is much larger with a wingspan of 35–39 mm. The forewings are brown, speckled with black and marked with a bold white branched basal streak which gives the species its common name. The hindwings are dark brown with a white fringe. This moth often flies during the day, especially in warm weather, and is attracted to a range of flowers. It also flies at night and is attracted to light. The adults are on the wing from July to September.

see http://ukmoths.org.uk/show.php?bf=2360

Ear moth – Noctuidae – Amphipoea oculea

Ear Moth Amphipoea oculea

Occurring over much of Britain, this has a more widespread distribution than the other British ‘Ear’ moths.

It tends to favour damp habitats and flies in one generation, from July to September.

The larvae feed at the base of various grasses and low plants, on the stems and roots.

and my husband photographed a white ermine moth caterpillar, safe from birds because they are poisonous.

Crawling fast along the ground, the poisonous (to birds) White Ermine moth larvae

Crawling fast along the ground, the poisonous (to birds) White Ermine moth larvae


White Ermine Spilosoma lubricipeda
(Linnaeus, 1758)
Wingspan 34-48 mm.

Widely distributed and fairly common over much of Britain, there is considerable variation in the degree of black speckling, and in certain parts of Scotland, there are forms with a buffish ground colour.

It generally flies from May to July, sometimes later in the south.

The hairy larvae feed on a variety of herbaceous plants, such as Stinging nettle, Scotch broom, Alfalfa and the common dandelion.

Later in September I returned to the ragwort high on the fells and was delighted to find two Haworth’s Minor moths, they usually feed on cotton grass, and the larva of the most toxic moth in Britain, the Cinnabar Moth always living on Ragwort, the poisonous plant to animals such as horses. The only creature attracted and able to eat this poisonous moth is the cuckoo.

Cinnabar moth larvae on ragwort

Cinnabar moth larvae on ragwort


An interesting note from:

http://en.wikipedia.org/wiki/Cinnabar_moth

The larvae absorb toxic and bitter tasting alkaloid substances from the foodplants, and assimilate them, becoming unpalatable themselves. The bright colours of both the larvae and the moths act as warning signs, so they are seldom eaten by predators. An exception is among different species of Cuckoo which eat hairy and poisonous caterpillars including cinnabar moth larvae.

Haworth's Minor moth on ragwort

Haworth’s Minor moth on ragwort

On the 15th September I saw the Broom Moth Larva and caught it in an old
plant pot to take a picture. Not a good idea, poor resolution, but still,
you get the idea.

From UK Moths website:

Noctuidae » Hadeninae

Broom Moth Melanchra pisi
(Linnaeus, 1758)

Broom Moth Melanchra pisi

Larva

2163 Broom Moth Melanchra pisi
(Linnaeus, 1758)
Wingspan 32-37 mm.

A very variable species, with the ground colour varying between greyish
brown to a dark chestnut colour, and the intensity of the markings varying
too.

Inhabiting open woodland and heathland, it is quite common in most of Britain.

It flies between May and July, and is attracted to light.

The distinctive brown and yellow striped caterpillar feeds not only on broom
(Cytisus scoparius), but also on bracken (Pteridium aquilinum) and other trees and plants.

Broom moth larva

Broom moth larva


Despite the wonderful summer, I did not see any of the variety of moths I have recorded in recent years. Certainly none in my garden. It is possible the garden I have developed from a field of thistles to a wildflower garden, has attracted more predators who have eaten the pupae before they had a chance to emerge. The bitter cold May could have had an impact too. Whatever the reason, I had to trek some distance to find any moths at all.

Butterflies

Peacock butterfly arriving too late for thistle nectar

Peacock butterfly arriving too late for thistle nectar


After the emergence of the peacock amidst a small number of small tortoishell, all competing for the thistles which were going to seed, the only other butterfly in September to be seen most sunny days was the green-veined white. Since it survives well at high altitudes, that is no surprise. But the peacocks were gone before my autumn glory sedum flowered, so were the red admirals, and in previous years they swarm this high nectar plant. Sir David Attenborough is correct. There are fewer butterflies than at any time in his life (or mine), this year.

The day after writing this, I received word from Butterfly Conservation that this had been a ‘bonanza’ year for butterflies and moths. Great news, but somehow this neck of the woods has seen its worst year.

Advertisements

About borderslynn

Retired, living in the Scottish Borders after living most of my life in cities in England. I can now indulge my interest in all aspects of living close to nature in a wild landscape. I live on what was once the Iapetus Ocean which took millions of years to travel from the Southern Hemisphere to here in the Northern Hemisphere. That set me thinking and questioning and seeking answers.
This entry was posted in Uncategorized and tagged , , . Bookmark the permalink.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s