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Another Mild Winter - so far!

24/1/2016

by Lesley McLaren

As a swathe of eastern USA is buried under massive amounts of snow, temperatures continue to remain mild in much of Europe, including here. El Nino is having quite an effect this winter.

Back in mid December the mimosas were beginning to show yellow, and bougainvilleas were still developing new flowers. This month gorse is in full bloom in hedgerows and hills - and attracting plenty of bees. New leaves have appeared on my olive and lemon tree, and are on the verge of opening on my red robin hedge. Lots of spring-flowering plants are already out - even geraniums left from last summer! - and gardens are looking positively colourful.

Birds are tuning up and I've seen a pair of collared doves mating already. There are some butterflies about too - red admiral in particular, and I've seen one clouded yellow - prematurely out of hibernation.

With midday temperatures sometimes around 20ºC, and few significant frosts, none of this is surprising. If we don't get a cold snap in February to slow everything down again it will be interesting to see what the knock-on effect of all this is later in the year.

But not everything is early. My camelia has started flowering bang on time this month, and my almond tree, which usually flowers later than most (in February) looks like being on schedule too.

I wonder how creatures such as metamorphosing caterpillars fare. Can the process speed up or slow down according to the weather?

I'm especially interested, having discovered this pupa attached to the wall by our garage.

At first glance it looks very plain and boring. Which is doubtless part of nature's grand design. Not much point making yourself conspicuous to predators. It would be better camouflaged - and perhaps more sheltered - in a less open spot, though. Amazing to see how it's held in place by such a fragile-looking silk thread.

It's quite big, and those horn-like protrusions look interesting, so I've done some internet research to see what it might turn into. And the answer is this:

A Scarce Swallowtail. One of my favourites! I feel very honoured and just hope it survives the next few weeks, to emerge safely in March. No doubt I'll miss the event but an empty pupa shell will tell its own story.

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Featherleg Differences

11/1/2016

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by Bruce Hyde

Dragonflies (the order Odonata) have two suborders - dragonfly (anisoptera meaning unequal wings) and damselfly (zygoptera meaning equal wings).

dragonflies (anisoptera) are larger and very much more obvious when you see them flying around.
damselflies (zygoptera) are normally quite small, and if you are not looking out for them you can easily walk right by without seeing them at all.

Having talked in an earlier blog about differences in one dragonfly species, Pincertails, I am going to cover a genus of damselfly which has 3 species in France: the Featherleg.

Damselflies are dainty insects. Featherlegs measure about 30 - 35 millimetres long overall, and their abdomen is only just over 1 mm thick. So certain parts of the body from which positive identifications can sometimes be made are very small - indeed some of the details on the pronotum (see further on) measure about one tenth of a millimetre across. In itself this presents useful photographic challenges (particularly as in getting my photos I never disturb the insect any more than possible, and never catch them).

The Featherleg (Platycnemis) forms in France are

White (P.latipes/L'Agrion blanchâtre)
Blue (P.pennipes/L'Agrion à larges pattes)
Orange (P. acutipennis/L'Agrion orangé)

Until recently I had thought that all three species were resident in our area, and I was having a lot of difficulty in determining which was which in my photo library, especially some of the females. I then looked more closely at a map in "Les Libellules de France, Belgique et Luxembourg" by Daniel Grand and Jean-Pierre Boudot - and life became easier. For some reason (unknown), in this South Eastern corner of France, the Blue featherleg is absent from Pyrénées-Orientales and rare in Aude. Thus the Orange and White forms are almost certainly the only ones I have been seeing. (At the same time one has to be aware that there just might be individual vagrants of the Blue form flying in from neighbouring areas).

So here are the 2 species this blog is about -

Typical Males

White Featherleg male (Platycnemis latipes)

Orange Featherleg male (Platycnemis acutipennis)

Superficially there is not a lot of difference between the males, except for the colour of the abdomen. However the females are very alike and, as always, the devil is in the detail!

Before going any further, lets look at some of the basic parts of a damselfly's anatomy.

Orange Featherleg female (Platycnemis acutipennis)

The Latin word Platycnemis comes from the Greek "platos" meaning flat and "cnernis" meaning shin. The tibia of the hind leg is wide and flat, more so in the case of the White Featherleg than the Orange, and all the legs have hairy bristles giving a somewhat feathery appearance.

Flat tibia with hairy edges

White Featherleg male (Platycnemis latipes)

There are a number of details of the insect's body from which one can make a positive identification. Thorax, abdomen and legs are all useful, although more so collectively than individually. In the case of females, the pronotum at the front of the thorax will give a positive ID, but it needs a very clear view, in good focus, as it is so very tiny (more about this later).

Featherlegs often have a double stripe running along the side of the thorax - the antehumeral stripe. While this feature is diagnostic of a featherleg, it is not always present.

White Featherleg male (Platycnemis latipes)

Males can quickly be distinguished from females by the appendages at the end of the abdomen. Male appendages are claw shaped to grasp the female when they are mating. Female appendages are contained in the swollen end of the abdomen.

White Featherleg male appendages

White Featherleg female appendages

When mating they often form into a heart shape, which is quite charming -

White Featherlegs mating (Platycnemis latipes)

Males of the two species are separated by their colour when they are mature; females tend to be similarly coloured and are distinguished by features of their pronotum (see below) and to some extent by leg markings.

Male Featherlegs
The typical male White featherleg has a white abdomen, often looking porcelain-like or translucent, whereas its Orange counterpart has an orange body. They both have blue eyes and there are black markings on the last few segments of the abdomen, although the extent of these is variable.

White Featherleg male (Platycnemis latipes)

Orange Featherleg male (Platycnemis acutipennis)

Looking more closely at the legs it can be seen that the White has got broader, flatter tibias than the Orange.

White Featherleg male, broader, flatter tibias.

Orange Featherleg male, tibias less broad

Male Whites have a stripe running down the middle tibia which extends about one third of the way; this stripe is usually absent from the hind tibia. The Orange has a stripe on the middle tibia which goes all the way down, and one on the hind tibia that goes about half way down. These features are diagnostic of the male (females are different).

White Featherleg male, middle tibia stripe

Orange Featherleg male, middle and hind tibia stripes

The eyes of all featherleg species, both male and female, are widely spaced. In the case of males they are an attractive blue colour.

White Featherleg male eyes (Platycnemis latipes)

Orange Featherleg male eyes (Platycnemis acutipennis)

Female Featherlegs
The females are harder to tell apart. Although the typical Orange female often has a darker coloured abdomen, this is not always so as the colour probably darkens as the insect get older. Immature females of both species are very similar.

Typical Females

White Featherleg female (Platycnemis latipes)

Orange Featherleg female (Platycnemis acutipennis)

The tibias of the female White are not as broad as the male, and in the case of the Orange they are not broadened at all. Unlike the males, the stripes on the tibias cannot reliably be used for identification, although in the Orange the stripes usually go at least half way down the tibia on all legs.

The eyes of both featherlegs are variable, some having blue patches and others being brownish for instance; the colours can look as though they are in layers. Here are a couple of examples.

White Featherleg female (Platycnemis latipes)

Orange Featherleg female (Platycnemis acutipennis)

Pronotum
The most certain way of separating a female White featherleg from an Orange is by carefully examining the pronotum. This is not easy and one has either to be very close indeed or have a detailed photo.

This picture shows the pronotum of a female White featherleg. It is shaped like an inverted "V" on top of the thorax where the front legs join. In this case the colour is light brown, but it can vary and is sometimes black.

White Featherleg female (Platycnemis latipes) pronotum

The White featherleg's pronotum has a clear lump on the top, is a bit knobbly and has very small bumps on each side at the lower end.

Compare this with the pronotum of an Orange featherleg where, instead of small bumps, there are large spikes (technically "sublateral spines"). This feature may not be very obvious as the distance across the body from spike to spike is only about 1mm; this added to the relative shyness of Orange featherlegs makes the getting of detailed pictures quite difficult.

Orange Featherleg female (Platycnemis acutipennis) pronotum spike

A slight aid to identification is the flight season. White featherlegs fly from mid-June until late September with the main months being July and August. Orange featherlegs fly from late May until mid-August, with the main months being June and July. These periods are not fixed and can be a week or two longer at either end.

Featherlegs like slowly running water such as some reaches of the River Tech, although I have seen them on canals.

They are often approachable, especially the Whites which almost seem to enjoy being on camera!

Damselfly habitat on the River Tech

Males like to perch on low vegetation near a river bank, and search for prey and mates with a slow zig-zagging or bouncing flight. Their wide tibias are not used in courtship, but as threatening behaviour to other males of the same species in flight.

Both the featherleg types in this blog are found in southern France, the Orange occupying south of a line from roughly the Cherbourg peninsula to Monaco, and the White south of a line from Bordeaux to Monaco.

In this blog I am referring only to featherlegs I have photographed on the banks of the river Tech near Montesquieu-des-Albères. In other areas of France they may have slightly different characteristics and may be easier (or harder) to identify.

There is little better than sitting in the shade on a river bank on a sunny day watching the fascinating behaviour of these tiny insects.

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Another Mild Winter - so far!

Featherleg Differences

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Another Mild Winter - so far!

﻿Featherleg Differences

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Featherleg Differences