Saturday, 31 August 2013

Newborn Pholcus spider

A female Pholcus phalangiodes carrying eggs has been in the outside toilet for over two weeks. Today, I noticed her shuffling a bit, and when I looked, the first spiderling had been born and was sitting on the eggs. The spiderlings' folded legs and rows of eyes are clearly visible through the egg shells. When I returned five hours later, the female was holding a fuzzy ball of baby spiderlings.

For more on Pholcus on BugBlog click here.

Male harvestman

The adult male harvestman Phalangium opilio is one of the easiest to identify due to its enlarged chelicerae and white underside. Despite their large chelicerae, they are harmless as they have no venom glands. Males appear to use their chelicerae to fight. This individual settled quite well on the white bowl, stopping to groom its long, thread-like 2nd legs. Harvestman often use these legs, the longest pair, as insects use their antennae, tapping objects with them to feel their way around, as an organ of touch. 
Grooming its 2nd leg using the palps.

A whole view of the individual, showing their longer second pair of legs, the blurry one was on the move.

Friday, 16 August 2013

Fresh Painted ladies

It has been almost four years that I haven't seen a Painted Lady, but today I had a nice surprise when I spotted one, high on the buddleia, amongst the dozen or so Peacocks that are so abundant these days. Painted Ladies are warmth-loving butterflies, unable to survive our winters, so before the cold sets in, they will migrate to the Mediterranean. This generation is the offspring of the butterflies that migrated to the UK in the spring, from southern countries, as far as Morocco. They arrived, mated, laid eggs, and the caterpillars fed on thistles, with the new generation being the fresh painted Ladies that will migrate south. Painted Ladies have mass migration years, in which they are much more numerous than usual, and these years appear to coincide with warm summers when Hummingbird Hawkmoths and Silver Y moths also migrate in large numbers to the UK. The last mass migration year was in 2009.
 If you see Painted Ladies, you can contribute to the research into their migrations reporting your sighting to Butterfly Conservation Migrant Watch Survey.
  See previous posts on Painted Ladies in BugBlog.
The intricate patterns of the underwing of Painted Lady

Sunday, 11 August 2013

Looooong legs!

 This Dicranopalpus ramosus harvestman posed in the flattened, all legs stretched posture typical of the species. There were lots of them sitting on headstones in my local cemetery today. When disturbed, they walk as a 'normal' harvestman', but soon after sit and stretch their legs again.

A close up of the individual above, a female.

Saturday, 10 August 2013

Legs for laying eggs

ResearchBlogging.orgMost Nymphalid butterflies, a group of large species that include the Peacock, Painted Lady, Comma and the Monarch, have modified forelegs, smaller than the rest of the legs and normally tucked in under the head. In the Peacock (above) the forelegs are relatively large, but not used for walking and they even have the same dark colour as the body, giving the impression that the butterfly has only four legs. Why is this? Despite their vestigial appearance, experiments have shown that the forelegs have a very important function, especially in females. In the investigated Nymphalid species (mainly the Monarch and the Queen butterfly), the tips of the reduced forelegs in females - but not males - have sensory organs associated to spines, which they use to recognise specific chemicals from the larval foodplant when ovipositing. They drum the leaves with their forelegs, puncturing the leaves and releasing plant chemicals allowing their receptors to detect them (what is known as contact chemorreception). The antennae and the tips of the other legs also contribute to selecting the foodplant, with tapping with the antennae and drumming with the mid legs also observed when selecting foodplant. The forelegs are part of a very complex sensory system, possibly providing a 'backup' with the sensory spines protected from damage, by the forelegs being reduced and not being used for walking. Butterflies can be very selective in choosing foodplants, as they not only have to determine the species of plant, but also how healthy or how old the leaves are, so it is not surprising that they use a complex sensory system to assess this, which we are only beginning to understand.

This video from Arkive, shows a female Peacock tapping a nettle leaf with its forelegs while laying eggs.

ARKive video - Peacock butterflies mating, laying eggs and caterpillars hatching

More information

Baur, R., Haribal, M., Renwich, J. A. A. and Staedler, E. (1998). Contact chemoreception related to host selection and oviposition behaviour in the monarch butterfly, Danaus plexippus Physiological Entomology, 23, 7-19 DOI: 10.1046/j.1365-3032.1998.2310007.x

Myers, Judith. 1969 Distribution of foodplant chemoreceptors on the female Florida queen butterfly, Danaus gilippus berenice (Nymphalidae)." J. Lepid. Soc 23: 196-198.

Pied hoverfly

At the higth of summer, I occasionally see this stunning hoverfly, the easy to recognise Scaeva pyrastri. I am going to follow NatureSpot and others and use a common name, Pied Hoverfly, although swift hoverfly would be equally fitting to this migrant, quick flier. It is that time of the year when each flower in the garden is being visited by hoverflies, and the flowering fennel is attracting quite a few.

Thursday, 8 August 2013

Be quiet to get close to feeding Silver Ys

A still, balmy night, there are many Silver Y moths feeding on the garden flowers: lavender, perennial peas and buddleia. I always have trouble taking photos of the Silver Ys, they are so flighty! A step forward and they all disperse. A typical shot when I am outside is like the one above. My best shots have always been from behind the conservatory window. Today I understood why. If found out that you want to get close to these moths you need to be quiet. Why did this surprise me? I knew moths are able to hear bat ultrasounds and respond with erratic flight and even dropping to the ground, I even wrote a post about it. But there is nothing like first hand experience for learning. I tried to take shots from the cloud of silver Ys feeding in the buddleia tonight, they were visible in the dusk light as hovering silouettes by the profile of the large flowers. And then, as I approached, camera pointing up and triying to decide which one to shoot, I stepped on a crunchy leave inadvertently. The whole cloud of moths responded instantly by flying in different directions: of course they can hear! Many sounds we make while moving about are actually ultrasounds (click your fingers near a bat detector to test this). I bet walking on my pebbly path does this too, and this was what was keeping them away. I moved slowly, placing each foot carefully and slowly on the ground. Stood next to the buddleia and waited until the silver Ys came back and resumed their feeding. And this time managed some outdoor clear shots.

Catching the wind

The last couple of weeks have witnessed increased activity of garden ants. It is the season when winged ants (males and queens) take to the air forming swarms. Today I noticed groups of queens emerging from a nest in the garden. The queens climbed over the plants, warmed up their wing muscles and took to the air. They often land straight away unless they can get high enough and ride the breeze. This was that this winged ant was doing, with head and antennae outstretched, it checked if it was the right time to fly. The dark clouds in the background are also typical of flying ant days, as the prefer stormy, warm weather to emerge.
The lucky ones will mate in the air and come back to the ground, lose their wings and find a suitable site to start a nest. Many will perish though, eaten by birds or spiders.
 If you notice flying ants where you live, you can submit your record to the Flying Ant Survey, organised by the Society of Biology. It only needs a couple of minutes to fill the form.

Monday, 5 August 2013

Peacock eyes

I just like this shot from today, a Peacock nectaring on buddleia, beautifully showing its four eye spots.

Sunday, 4 August 2013

Nymphalid riot

The buddleias are now in full bloom in the garden, and buzzing with bumblebees, droneflies and butterflies. Today it was a particularly wonderful day for butterflies. Eight species were feeding, or passing by the garden, but the 5 Peacocks on one buddleia at the same time must have been a first. A Comma and a Small Tortoiseshell accompanied them at some point. A Speckled Wood fluttered by the garden, not settling long enough for a photo. The three common white species were about, some egg laying and a darting skipper - which didn't settle either made an appearance too.
 The Peacocks spend most of the time feeding on the buddleias, occasionally settling on the wall or the ground for a spot of sunbathing. The Small Tortoiseshell sat on top of the fence, allowing me to take a photo of it at an unusual angle.
A great day for a Big Butterfly Count too.
Peacock underside, such an amazing contrast between the brightly coloured upper wing colours.
Peacock and Small Tortoiseshell together

Two of the five Peacocks feeding on the buddleia
Large white
Small White
Sunbathing on the ground
Comma, showing the paler underside of the summer generation

Friday, 2 August 2013

A new hornet-mimic hoverfly

 I found this large, colourful hoverfly feeding on Yarrow (Achilea millefolium) in the garden this evening. It is a male Volucella inanis, a hornet mimic which is also found in nests of wasps and hornets, where its larvae develop. Spot on, its numbers peak at the beginning of August. The entry in Stubbs and Falk's British Hoverflies notes that its distribution range is expanding north, and being the first time I come across this species, I checked the NBN Gateway: no records for East Yorkshire or anywhere north of the Humber. Another species expanding its range due to climate change? I should start keeping a list.

UPDATE 4/08/2013. Barry Warrington e-mailed me with some more info about the species in East Yorskshire: "V. inanis is scarce in our County. I recently found one a couple of weeks back and having liaised with the YNU Diptera recorder and checked the Watsonian Checklist, my find was the first for East Yorkshire. It is clearly spreading well and quickly, with it being most common in VC63."