Wednesday, 23 May 2012

Crikey, its hot at last!

A slow walk down the access trail revealed two species of click beetles, the wasp beetle Clytus arietus and several good views of solitary wasps and hoverflies. Here is the first of the click beetles a deep black one. I did wonder whether it might be Hemicrepidius hirtus, a fairly common all black species (including its legs, important in ID) with obvious ridges down the elytra, as seen in these pictures I think.




the pectinate, or if you prefer, serrate, antennae:


and this is the second insect, demonstrating the more usual colour of click beetles, possibly an Athous species such as haemorrhoidalis or an Agriotes species such as lineatus. The larvae of species such as these are common agricultural pests known as wireworms!



These pictures show the angular processes at the posterior margin of the pronotum very clearly!




The next insect is one I have heard of, and seen photos of, before. it is the highly distinctive, and indeed unique, wasp beetle, Clytus arietis, of the family Cerambycidae or long-horn beetles:


There is nothing else like this in the Coleoptera, and whenever I have seen a picture of it, I have wanted to see it in real life. Why it would wish to imitate a wasp, when it is already such a tough cookie, is difficult to imagine. It really does appear to be genuine mimic, because it even makes jerky wasp-like movements on flowers, and a waspish buzz when threatened,  presumably to try to convince attackers that it is a genuine wasp! This one seems to have its legs all over the place, and hasn't tucked its pair of flying wings properly under the elytra either.

The elytra are rounded as seen here, and the colour pattern is as seen here. The yellow bands on the square pronotum are typical, with the posterior one divided, as it quite commonly is.The legs are orangeish although the femora are darker. All tibiae have an apical inner spine. Overall the beetle is about 9 - 13 mm long.

The adults are often found visiting flowers and are harmless. The larvae tend to live in dead wood, at first just under the bark, and later in the xylem. The wood used includes dead parts of living trees, dead trees or even fallen dry branches. There is plenty of all of these categories of dead wood along the Access Trail, so the larvae would have had plenty of choice for their homes!

The femora may actually appear quite short and broad, and specifically clavate, particularly in contrast to the apparently much longer thinner tibiae, as demonstrated in this unusual view taken from the rear of the beetle crawling from one leaf to another (unless this is just fore-shortening - it is!):


In the slightly serrate antennae the third segment is clearly longer than the fourth, an identification point worth noting. The first four segments are notably orange in contrast to the darker more apical segments


There were quite a few other insects around, including a few hoverflies. Here is the very common marmalade  fly, Episyrphus balteatus, I think a male, very battered, poor thing!



Here is another one, moderately small, but I have no idea of what species it might be. I took a wild guess at Cheilosia but it could well be a whole load of other things as well!




The next hoverfly is another very common one, a male Sphaerophoria scripta, a tiny and very characteristic species.


This is a much bigger hoverfly, but also a very common one, Eristalis tenax, the Drone Fly, with its wide dark facial stripe, and very black rear legs. This particular individual is very dark on the top of the abdomen, usually there are some clear orange sectors here:



Rather nice to see was an immature Common Blue Damselfly, Enallagma cyathigerum, settling quietly from its exploration of the bottom of the hedgerow, with the beautiful lilac colours of a newly emerged adult. The broad blue sub-humeral stripes, the lack of a "Coenagrion spur" on the sides of the thorax, and the dark mushroom on section 2 of the abdomen are indicative of the male of this species, separating it from other blue species such as the Azure Damselfly.


By now I was thinking I was doing really quite well for insects, and a solitary female bee a little further along proved me right when it looked a lot like Andrena chrysosceles. I thought I saw this species at least once before, on the Shepherds Needle down towards the Gravel Pits, but no-one replied to my posting of that insect on ispot for checking. Lets see if the ispot people can help me out this time! This bee was sitting on an ash leaflet on the edge of the Green Lane shaw, grooming itself gently. Because it was fairly still, it allowed a series of photographs, all in the same posture.

The reason I think it is chrysosceles is as follows. It is a smallish Andrena bee, with the typical shape and hairiness for the genus. It is also female because of the long brush of hairs (scopa) on the rear legs. The thorax is lightly coloured with tawny but not fulvous hairs. The abdomen is a relatively shiny glossy black and has very clear close knit bands of silvery hairs running across it (I have seen one picture on the BWARS website that might indicate these bands can be worn away a bit on the top surface, but this may also depend on the light). There appears to be a reddish tuft of hairs at the end of the abdomen. The legs are dark at the base, the femora, but bright gold-orange further down, at the tibiae, and this extends right to the end of the foot, the tarsi and metatarsi.


The male of the species is similar but has white hairs in a moustache on the face, with a white clypeus with two small black dots either side.

There was another female Andrena bee almost immediately, but very clearly of a different species. Actually I now think this is Andrena nitida (2021). This one was much more robust, again with a glossy black abdomen, but larger and more rounded, without the obvious white bands across the abdomen, or the thin white side tufts on the first segments of the abdomen.
 




Note the blackish hairs at the rear of the abdomen, though probably not a reliable character.

Friday, 18 May 2012

A grey Dene Park

Unfortunately I spent too much time trying to determine the law on the planning applications listed for our next parish meeting today, and it was very grey by the time I got Monty up to Dene Park. As on my last visit I then concentrated rather a lot on the first stretch of the ride, finding more or less the same populations as yesterday, but in addition there was my first Soldier Beetle or Cantharid of 2012. 

This turned out to be Cantharis pellucida. The features fitted this species more than the other very similar Cantharids, but I was pretty sure because of the adpressed grey hairs on the elytra, the black scutellum, the bright orange of the rounded prothorax, the orangey front legs and the orange and black mid and rear legs, the black head finishing up just in front of the eyes, and the mainly blackish antennae. The tarsi seemed quite flattened out. 





Another new insect for Dene Park was the Harlequin Beetle, Harmonia axyridis, significantly larger than the other ladybirds (14-spot and 7-spot) seen, and of a particular colour form I think, Harmonia axyridis succinea.

The other animal in large numbers was the Opilionid Harvestmen, standing sentry on the tops of the nettles, today definitely outnumbering the Nursery Web Spiders. In the picture below the long second pair of legs are acting as the harvestman's sensory "eyes", testing the environment for both food and threats!


Wednesday, 16 May 2012

Dene Park on a slightly better day


I went up to Dene Park at about 3 p.m. after an early morning Nightingale survey, three hours teaching in the morning and some admin in College after lunch.

The nettles and brambles by the side of the first ride slowed me down as they were well stocked with insects and spiders. There must have been aphids present I would imagine, as there were both 7-spot and 14-spot ladybirds in good numbers.

This is one variant of the 14-spot ladybird, Propylea quattuordecimpunctata, a little bit variable in detail. This is a generalist aphid feeder, common all across the UK. It can secrete toxic compounds to deter predators, and is quite a bit smaller than the common red and black 7-spot. Tends to hibernate low down in vegetation.


This other is I think the same species, but is a less usual colour variant. However the mid-line suture is still black in colour:


And this is the very common 7-spot ladybird, Coccinella septempunctata, also a generalist aphid feeder, found across the paleartic. It can also secrete toxic alkaloids to deter predators. It hibernates low down in herbage or in conifer foliage. There is a tiny fly here as well!


There were also quite a lot of nursery web spiders, Pisaura mirabilis, sitting on the tops of the nettle plants, ready to hunt or grab anything that goes past I imagine. I think this is a very common spider, of paleartic distribution, its identity indicated by the overall shape, abdominal colour pattern (variable in detail) and central fringe line over the cephalothorax. Here are three different colour forms, all fairly close together, all very different in colour:




Mixed in with the nursery web spiders, there were these animals, which are harvestmen, the order Opiliones, according to Ophrys on ispot. I should have thought more carefully before I put this picture up!


Perhaps taking dead food material from the spiders and/or harvestmen, there were plenty of scorpion flies around. This one is likely to be



and a bit further on I found this smaller spider:



I also saw the nymph of a bush-cricket, probably the Dark Bush-cricket, Pholidoptera griseoaptera, thanks to Michael Skelton on ispot.


and then, to my intense delight, I was sure I saw a wonderful hoverfly, Leucozona lucorum, beautifully coloured and furry, with dark wing markings, that I have hoped to see for a while. Sadly I only managed a quick "partial" photograph before it flew off into the gloom of the woods away from the path.


There were quite a few hairy shieldbugs, or sloe bugs, Dolycoris baccarum, on the vegetation triangle in the middle of the path. I didn't notice any sloe bushes close by.


and then a very interesting looking sawfly, which I originally thought was a wasp, with a creamy white clypeus and shoulder flashes, black coxae, apical parts of rear legs and overall bodies, orangey tegulae and otherwise orangey legs. Perhaps Tenthredo atra, or another species.





I also disentangled a tortrix caterpillar from some webbed hornbeam leaves. This could be one of a number of tortrix species that attack hornbeams.


Finally there was this tiny Andrena(or something else?) bee on a dandelion flower,


This next one, seen a little bit earlier, was much bigger: