Broad-bodied Chasers

I popped at the YWT local wildlife garden after work. The staff alerted me to the presence of a Broad-bodied chaser on a patch of Red Campion. I popped out to find it there straight away. It sat on the flowers and repeatedly darted to catch an insect, only to return to the same perch, flycatcher style. It didn't have to fly far as it was warm and sunny and there were plenty of small insects about. This, one of the most spectacular of our dragonflies, is my first species for the Hull Dragons challenge! A quick walk around the pond revealed there were at least 5 individuals about, each sallying from their favoured perch hunting almost in succession. All of them had yellow abdomens, including two males, indicating that they had emerged recently, most likely from the pond in the garden. They mostly ignored one another, despite being in quite close proximity, another sign that their male territorial behaviour hadn't kicked in. Despite their amazing colour, they are quite cryptic and merge into the foliage as soon as they stop.

Immature male.

This species is still uncommon in the Hull area, with only a handful of records. As I covered in a previous post, it was unknown in south east Yorkshire before 1995, although it is becoming more widespread. It is a good colonist and one of the earliest dragonflies to breed in new ponds. The pond in the garden was re-dug in February 2016, and given that the larvae only emerge after 2 or three years it is likely that the species bred in the pond the first summer after it was refilled.

The pond being re-lined in February 2016. I will post some photos of the pond as it is now in a future post. 

A walk around the pond revealed one, possibly two Azure damselflies. It is not a very large pond, but always interesting and I have records of a good range of damselflies and dragonflies: Common Emerald, Azure Damselfly, Blue-tailed, Common Darter, Ruddy Darter, Southern Hawker and Migrant Hawker. Broad-bodied Chaser is a great addition to the list!

Another immature male. Note the white reflections on the wing indicating that this individual has emerged very recently (teneral)

An immature female, note the wider abdomen in comparison with the males.

Immature female.

Egg laying Southern Hawker

On the way back from work I popped in my local wildlife garden. I was looking for dragonfly exuviae in the small pond when I gasped: A female Southern Hawker had materialised like out of nowhere and was hovering inches from my face. This is a large and inquisitive dragonfly, with a striking apple green, yellow and black pattern, which often approaches humans when they walk on their flight path. She took no notice of me and landed just by my feet, on the side of the pond-dipping platform. She was egg laying! I watched, mesmerised, how the tip of her abdomen appeared to direct proceedings, making searching movements on the pond lining, in a caterpillar-like fashion. After a few moments she flew low across the rushes growing in the pond, her wings clashing with the leaves. She landed nearby on the shore and started egg laying again. Taking her time, her abdomen appeared to 'look' for crevices amongst the mosses and litter, just a few centimetres over the pond surface.
 There was no male about. Hawkers oviposit on their own. 

Oviposition sites
Hawkers often lay their eggs endophytically, which means inserted into plants, mud or debris or wood on the pond margin, as opposed to exophytically, meaning dispersed on water. However this species appears to often chose odd places as substrate, and indeed, in the space of 10 minutes the female today had probed or laid in several places in the pond:

Probing on pond liner...

on mosses at the pond margin...

...on the decaying leaves of aquatic plants.

on the wooden panels of the pond-dipping platform.

 Having recently read the New Naturalist volume on Dragonflies, I wasn't too surprised. Philip Corbet and Stephen Brooks compiled a list of totally bizarre substrates chosen by Southern Hawker females to lay eggs. These included:
-A brown woolly jumper
-A wellington boot
-Someones ankle
-A dog's rump
-The skin of a Yellow-bellied toad

Corbet and Brooks remarked that in some of these cases the female might be just investigating the suitability of the particular substrate chosen, as opposed to ovipositing.

The Southern Hawker female hovered a few times by the pond and then moved on, hawking low along the garden path by the hedge a few times and exploring the bushes in the typical fashion of the Southern Hawker. This low flight is a behaviour that unfortunately, makes this species a frequent prey of cats.

More information
Klaas-Douwe B Dijkstra. 2006. Field Guide to the Dragonflies of Britain and Europe. Illustrated by Richard Lewington. British Wildlife Publishing. 320 pp.

Philip Corbet and Stephen Brooks. 2008. Dragonflies.  The New Naturalist Series. harper Collins Publishers, London. 454 pp.

Emerging damselfly

I went to the wildlife garden on my walk to the school run. I was lucky to find a just emerged damselfly. It was sitting on top of its larval skin (top shot) on a leaf. There were other dry exuviae on the same leaf and an immature Azure Damselfly, so I guess the newly emerged individual is this species too. I was surprised to find this emergence as it has been a dull, cold day with a bit of a drizzle at times.

A teneral (recently emerge immature) Azure Damselfly on the same leaf.

A photo of the leaf with the teneral individual on top, its exuviae and the newly emerged one at the bottom.

The wings have started to expand. Note the relatively thick abdomen.

The fully extended wings. The individual is still very green and soft, it will slowly acquire its black markings and later the mature colours. 

Here be dragons!

This year I'm taking a special interest on dragonflies. They are a relatively small group, species are easy to identify in the field and they offer a range behaviours relatively easy to watch. In July I atended an FSC course on identification of aquatic macroinvertebrates and I immediately wanted to learn to identify dragonfly and damselfly larvae. A few days after the course I visited my local wildlife garden and went to the pond to check invertebrates. Something on the leaves of an aquatic plant called my attention. It was a dragonfly exuvia, the moulted skin of a nymph as the adult dragonfly emerges! 

My first dragonfly exuviae.

Dragonflies have incomplete metamorphosis, which means they lack a pupal stage. The dragonfly eggs hatch into nymphs which grow though several stages as aquatic predators. Nymphs lack functional wings or reproductive organs. The final nymphal stage will creep out of water and moult into an adult. There wasn't just a single exuvia though, there appeared to have been a mass emergence of Common Darter dragonflies and I counted over 50 of them. 

Several visible exuviae on iris leaves (13/07/17).

These are all the the exuviae I could reach from one end of the pond.

A close up of one of the exuvia looking quite intact. The adult emerges though the thorax.

The following week I had the chance to pop in the wildlife garden one morning. I checked the leaves for more exuviae and I was surprised to find two emerging dragonflies!

A Common Darter just emerging, head down, showing how the old nymph skin holds it to the leaf. On the top shot, one already drying its wings, folded back and still lacking pigmentation (both photos on 21/07/17).

This fresh adult male Common Darter, perhaps from the first emerging batch, was sunbathing by the pond.

A pair of common field grasshoppers

 I found a pair of common field grasshoppers, Chorthippus brunneus, in the wildlife garden. They were basking on a stone near each other (see photo below) and I managed to approach closely, so that their distinctive hairy underside is visible. They are a variable species, with pink and orange forms, but this population is made of brown, mottled ones. They are winged, and therefore good colonisers, with their folded wings sticking beyond their knees. The male is smaller and has a brightly coloured abdomen and longer antennae. Check the species page of Orthoptera & Allied Insects for more information.

Pirate spider eyespots?

Wolf Pirate Spiders (likely Pirata piraticus, but there is a similar species, P. tenuitarsis) are one of my favourite spiders, their existence in the boundary of water and land, and their ability to walk and run on water makes them fascinating. A few days ago at the wildlife garden, I discovered a curious fact about them while looking at a photo of a female carrying an egg sac. The female was lodged at an angle on some leaves and I did a double take: it gave me the impression that the abdomen of the spider was in fact, its face. This impression was due to two paired white spots on the female's abdomen looking like eyes. Instead of a spider facing away with her egg sac attached to its abdomen, it looked like a spider looking forward, while carrying its egg sac on its jaws, in the way of nursery web spiders. Pirate spider eyespots? Wolf pirate spiders have paired line of white spots on their abdomen, so I wondered if it was just this particular individual that casually had the spots in the shape and area to give this impression. I checked my photos of this spider and found at least two others with the same spots, one also carrying an egg sac. I also found other photos on the web of this species with the same abdominal spots.

Another Pirata sp with egg sac and 'eyespots' 22/07/2014, same habitat

For comparison, a female nursery web spider carrying her egg sac with her chelicerae.

 Only photos taken in a particular angle, of the spider facing away show this, and I guess everybody prefers a front shot of a spider, so I think this pattern is probably found in the species at least regularly, and not only in the females, this side view of the spider allows to see the larger spot towards the end of the line of spots in a male

24/05/2014

A frontal view of the same male showing his enlarge palps:

Have these spots evolved due to them giving an impression of eyes to visual predators, as the eyespots found in some caterpillars and butterflies? In some cases eyespots function to startle a predator giving the impression of a different, larger animal (like the elephant moth caterpillar, the peacock butterfly or this amazing tropical caterpillar), instead, in the wolf pirate spider the eyespots would work like those found at the rear end of some fishes and butterflies, whose function might be to trick or confuse a predator as to where the head of the animal actually is. In fact, eyespots are not unheard of in spiders.

 Why would this be beneficial to this spider? What follows is only speculation, but apparently, wolf pirate spiders live in retreats in moss at the shore of ponds, and females carrying egg sacs often expose the egg sac to the sun at the retreat entrance, while the female remains inside. This could put the female in danger of predation, as she would be less able to detect danger, so the eyespots could afford some protection to the mother and its offspring to be, but I am not aware of any research into the evolution of these eyespots.

With thanks to Catherine Scott (@cataranea) for discussing this on twitter before I wrote the post.

A Slug day

As predicted, it rained all night and most of the morning. In the afternoon, the rain turned to drizzle and eventually stopped. This was an ideal day slugs, so my youngest daughter and I went to the wildlife garden to try and see some. Slugs don't have many fans. Many gardeners detest them and fight the slug wars with any means available. Out of the 40+ British species, many of them introduced, some are indeed serious agricultural pests specialising on feeding on living plant tissue. Slugs as a group, however, are ecologically very diverse and most species cause little or no damage feeding on algae, decaying plants, lichens, carrion, or fungi. A few species are earthworm predators. Slugs are not a natural group, they are a mixed bag of snails which have lost their shells: British slugs are the result of four different evolutionary shell loses, each group being more closely related to a different snail family, but more on that on a future post.
 Slugs were plentiful in the garden today and gave a good idea of the diversity of the British fauna. A nice feature of slugs is that they can be easily collected by hand - provided you don't mind getting covered in their mucus - and they are best identified live, so no collecting is necessary (except for some species where dissection is necessary for identification). I tried to get photos of the right side of the slug, with shows the breathing pore and other diagnostic characters, and used the Slugs of Britain and Ireland FSC guide by Ben Rowson and colleagues to identify them. I am no expert, and if you see any misidentification, I will be grateful if you let me know.
 We first came across some large Arion slugs (above photo). These are often active and out and about during the day. The one on the top shot was feeding quite high up on an angelica plant. When disturbed (e.g. poked with a finger), these slugs make a semispherical hump. The first one we came across, a very dark one, started rocking from side to side, a dancing slug was a good start! Only a couple of very variable species, Arion ater and Arion rufus will show this rocking response. Despite its dark colour, this one appears to fits better with Arion rufus, which has a bright orange foot fringe, but Arion often hybridise and species identification is tricky, especially in disturbed habitats.

This was another large Arion, which wasn't as keen to dance:

An Arion adopting its humped defence position.

We found the next slug, the Iberian Threeband Slug, Ambigolimax valentinus, inside an upturned plastic pot, which is fitting as this species is thought to have been introduced initially to greenhouses, but now it is readily found outdoors.

Ambigolimax valentinus

And now to our 'kitchen slug': the Green Cellar Slug, Limacus maculatus. A large, strictly nocturnal species able to squeeze through the tiniest cracks. If you go out into your garden at night, you are likely to see this slug in large numbers. They will often feed on other dead slugs or snails that had the misfortune of being squished on paths during the day. The ones inside our house will feed on cat food if there is any left. This was found together with others under an upturned large plastic tray.

Limacus maculatus

We lifted a few logs and there I found one of my favourite slugs, the Worm Slug, Boettgerilla pallens. I've never seen it in my garden, but it is common in the Wildlife Garden. It is an introduced species first detected in the UK in 1972, when it was already widespread. It was first described from mountain forests in the Caucasus and since then it has spread to western Europe. It is a mainly detritivorous slug, long and thin when moving, reminiscent of a worm. It lives underground, down to 60 cm deep, and moves through earthworm burrows.

The Worm Slug on the log where we found it.

Worm slug on the white bowl.

I got to Deroceras invadens/panormitanum for the next two slugs. Although they look quite different, they look like they have a hump and a truncated tail.

The last one is also a Deroceras, but the tail end is not as truncated, so I got to Deroceras reticulatum.

Deroceras reticulatum

A solitary bee quartet

I had so many wild things this summery sunny day that if was hard to settle for an invertebrate group to feature. For lunch I went out with fellow wildlife-lovers Robert Jaques and Callum MacGregor, and tried to capture some hoverflies. Hoverflies were indeed a good candidate for my wild group today as there were plenty, and of many species. Many males were hovering, but a couple of Myathropa florea males managed to sit on my hand, Robert's shoulder and Callums head and avoid the insect net altogether. Episyrphus balteatus, the marmalade fly, were also hovering, and the beautifully metallic Epistrophe eligans. Then I spotted a new spider, with a caterpillar on its web, and then another, would I feature spiders? Then a Red Mason bee started feeding on Buttercups, maybe a wild solitary bee day?

Female Red Mason bee, Osmia bicornis on buttercups. One of her 'horns' is visible at the front of her head. She uses its horns to mould mud she uses to seal her nest.

 Later after work I popped in for ten minutes in the wildlife garden. It was quite warm at the time. A leaf-cutter bee was feeding on thyme, and then chives. Its white and golden mittens flashed as it fed, a Willoughby's leaf cutter bee. Definitely a solitary bee day!

Male Willoughby Leaf-cutter bee, one of the easiest to identify by its front legs, which are covered on white-golden hairs in the shape of mittens, just visible here.

Back home I went to the sage. I had seen a favourite bee of mine yesterday very briefly. Anthophora furcata, a male which didn't settle, patrolling around the sage and the hedge woundwort. This is a rich brown bee with a very long tongue. Males have a yellow face and they have a strong preference for hedge woundwort, but also like several others flowers with deep corollas. Males appear, as many other bees, earlier in the season, settle in an area with their favourite flowers and check other bees, often head-butting them, while in search of females. And there he was, lovely and fresh. He even stopped the frantic patrolling to settle on a sage leaf to bask for a while, its back and face covered on pollen.

A male Anthophora furcata.

As I watched the A. furcata, a smaller bee caught my attention. It was a female Osmia caerulescens. This is a long tongued bee too, females have a bluish tinge and white hairs on stripes on its abdomen. After feeding on the sage, the bee stopped and stretched its tongue several times.

Female Osmia caerulescens

A female Osmia bicornis in the garden on the wallflower Erysimum 'Bowles mauve'.

If you'd like to learn to identify solitary bees, the Bees, Wasps and Ants Recording Society is a wonderful resource. Identification sheets for common solitary bees, often found in gardens are available too. There are 205 species, many hard to identify, but a few common ones are easy to identify once you become familiar with them.