The Green Meshweaver gets to Hull

 

Another post on a rapidly expanding species, this time a small spider, the Green Meshweaver, Nigma walckenaeri. All started on Saturday, during the YNU AGM in the University of Hull, where spider expert  Geoff Oxford, showed us a specimen he had just collected from the university grounds, a tiny green spider that is currently expanding its range across the UK and now colonising Yorkshire. We all admired the individual, which had been collected with its web on a leaf. 

The first Nigma walckenaeri record from Hull.

After returning from the meeting, I searched the garden ivy, and since I've been searching ivy and holly, which are favoured leaves to weave it's mesh. Nigma walckenaeri  chooses curled leaves, so it can take advantage of this to hide under its little web. As other regular character in this blog, Amaurobius, Nigma is a cribellate silk weaver. 

Today, I took a local walk and came across a magnificent mature ivy, south east facing. I started searching its leaves, wondering if I had the wrong search image in my mind. It didn't take long to find a Nigma.

Nigma walckenaeri  habitat.

There it was! A light-touch web of blueish threads with the green spider sitting, well camouflaged, underneath.

I moved part of the web aside to have a closer look (also top shot). This is a female, with her whole body green. Once I had seen one, I found another, and another, almost every ivy leaf had it's little Nigma in it. 

A male, with its brown cephalothorax.

This individual was busy weaving its web.

I even spotted a male (with reddish-brown opistosoma) on the edge of a female's web.

Until 1993 it was only found in London and the home counties, and it is associated to parks and gardens. Since then it has been steadily spreading north. I'll keep a look for it in the garden!

Urban Purple Hairstreaks

I had a most unexpected and delightful walk to work this morning. As I was about to cross Westbourne Avenue, where a water leak has been repair, a passer-by flushed a small butterfly from the barriers. I thought it was probably a Holly Blue, but when it settled with wings closed on a privet hedge nearby, I realised it was a hairstreak! I fumbled for my camera as it fluttered along the hedge into a front garden, where it sat with wings open. With shaking hands, I was able to take a photo (below), confirming the id as Purple Hairstreak! 

The first Purple Hairstreak

The Avenues is a very leafy part of Hull, with large gardens often holding large trees. In fact, there is a mature, spectacular oak at the back of the Adult Education Centre on Park Avenue not far away, and, as I walked past, I wondered if the wind might have blown the small butterfly away. I carried onto Jack Kaye fields. A Speckled Wood by the entrance to the fields, by an oak, reminded me to do a butterfly count, and I set an alarm on my phone to 15 min. I counted six Speckled Woods, as they squabbled around the trees. Then I moved onto the first glade. A small butterfly settled on a Whitebeam to bask in the sunshine. As I focused my camera, I got the feeling of being in a dream: it was another Purple Hairstreak! It has its wings closed and I took plenty of photos. 

Tree canopy butterflies

Purple Hairstreaks are canopy specialists, they spend much of their time on tree tops, around oaks (the larval food plant) and nearby trees, where they feed on honeydew. Although other species that obtain most of their food from honeydew, like Speckled Wood and Holly Blue, can occasionally be found feeding on flowers, or resting or fluttering low down, Purple Hairstreaks rarely come down to the lower level of trees, but they have been seen feeding on bramble or hemp-agrimony. They live up in the tree tops, and it is for this reason that they are easily missed. There are only 18 records of this species in East Yorkshire, mostly in nature reserves, but also at Snuff Mill Lane, just outside Hull, where I saw them in July and in Beverley Westwood, which has a sizeable population. They are not only found in woodland, but also along lanes and in parks with oaks. But, as these lovely, tiny butterflies, spend their adult lives up in tree canopies gorging on honeydew, they are likely to be overlooked and under-recorded. In the last few weeks I've been looking for them at Jack Kaye, staring into that small oak by the entrance, so although I was beyond pleased to find it, I was a bit astounded that it had actually happened. 

I will keep an eye on this area to check if these are isolated individuals or if there is a colony, and I plan to keep looking at oaks, wherever they are!