Tree sculptures and lesser stag beetles

In the last three weeks, I have been coming across Lesser Stag Beetles (Dorcus parallelipipedus) dead on the pavements in my street. June and July are peak emergence time for these dark, flattened beetles. Today we found 10 squished ones and a live one next to a chestnut tree stump, is this were they were coming from? I got the impression that the beetles might have been seeking shelter under the wheels of a car parked next to the stump, and they were inadvertently squashed every time the car moved. This tree stump used to be a tree sculpture (here for a photo, yes, the car behind is the beetle squasher!). Old trees that have got too big are partially felled in our neighborhood to avoid subsidence and then carved into statues. The dry dead wood soon becomes peppered with many tiny beetle holes, which are taken over by little wasps to nest, accompanied by their suit of parasitoids. The sculpture was taken down last year as it had started to rot and become unstable. The remaining stump was as soft as crumble. When I looked into it today, many large exit holes were visible on the surface. I dug a bit into the rotting wood with a stick and it didn't take long to find a Lesser Stag Beetle larvae. They have a large head, strong dark mandibles to chew the rotting wood and a c-shaped body curled underneath. The larva was very active, it turned round and quickly moved away hiding into the wood. Millipedes, woodlice and earthworms shared the dead wood with the beetle larva.

The collection of dead Lesser stag Beetles. The one on the bottom left-hand side is a large male with impressive jaws. There is huge variation in size amongst individuals.

A close up of the stump with exit holes.

An overview of the Chestnut tree stump

A side view of the young larva

Lesser Stag Beetle larvae take over two years to develop, and several stages may coexist in the same stump. Adults also may live several years, so it is a shame so many are dead, but this stump probably holds many tens of larvae and many adults have probably already dispersed successfully after emergence. 

City butterflies: the Comma

11 September 2006, comma basking on clematis

I have recorded 18 species of butterflies since 2003 in the city of Hull. Four of these I see occasionally, or I have seen just once (White Letter Hairstreak, Brimstone, Orange Tip or Small Copper), species that are more at ease in the countryside. This leaves 14 species that are common enough in the city streets, parks and gardens. One of the most obvious October butterflies is the Comma, Polygonia c-album. This species is recognized by their bright orange background with dark marks and an unique ragged edge-looking wings. Its underside is quite dark in the overwintering generation, with a clear white 'c' in the hind wing: once it closes its wings, it looks like a withered old leaf. Its legs have elegant white stockings. I find the comma difficult to tell apart in flight from the Small Tortoiseshell.

10th October 2008, Comma basking on apple tree

 There are not many sources of nectar around in October; I have recorded commas feeding on Ivy, Buddleia and Cherry Laurel this autumn. In her treasure trove Butterfly Garden webpage, the late Linda Walls also cites Verbena, which flowers in October. The butterflies around this month are the overintering generation. They still fly on sunny days on the look out for nectar sources in preparation for winter. Although the odd individual interrupts overwintering on sunny winter days, they should wake up again at the end of March, ready to mate and lay their eggs.

25th September 2008, Comma feeding on cherry laurel 

The photos above show individuals from the overwintering generation. The one below is the only one I've got from a summer generation ('hutchinsoni'), taken on 8/07/07. Note that its underwings are much paler than the overwintering form.

The following graph shows my sightings for a OS grid square in Hull. it shows the butterfly overwinters from October to late March - frost season here - and the hibernating generation mates and dies off during april. No adults are seen in May and June, but the 'hutchinsoni' or summer generation emerges lays eggs and dies off in July. Finally, September sees a new generation of commas, which are non-reproducing and will overwinter.