Tuesday, 24 April 2012

Down by the riverside

Much of the river Deele is edged by tall trees which cast a deep shadow along much of its length. This creates a wonderful microclimate, ideal for a combination of woodland flowers and waterside insects. I like to visit at this time of year because it always serves up something of interest.

The area I visited is ripe with the aroma of Wild Garlic (Ramsons) at this time of year: the bank is covered with its delicate white flowers and strappy green leaves:

Ramsons (Wild Garlic) at the river Deele
The flower-heads emerge wrapped in a thin protective sheath which opens to reveal delicate, star-shaped flowers:

Ramsons flower-head with sheath
And a close-up reveals the delicate - almost translucent - nature of the petals:

Wild Garlic flower-head
Two other woodland flowers are also at their best at the moment:


And Wood Anemone:

Wood Anemone

Having (at last!) got my hands on some spider references, I have been making an effort to fill in some of the gaps in my identifications.

Tetragnatha extensa is usually found near water on low-level vegetation. This one was on Hogweed on the riverbank:

Tetragnatha extensa on Hogweed leaf
Note that its rear right leg is holding the 'tension thread' which allows it to hide, whilst still being able to detect when some insect is struggling in its web. New to my Species List.

Tetragnatha extensa is very closely related to the huge brown spiders that are often found in garages or bathrooms.

Up on the bridge I found Ivy in fruit:

Ivy fruit

And a nice profile shot of the hoverfly Platycheirus albimanus which is everywhere at the moment:

Platycheirus albimanus (female)
I often think that its fascia is very like a human profile.

I'm never quite sure to be dismayed or excited when I see a Pug moth that I don't recognise: I realise that they are very difficult to identify (and that means I'm going to spend quite a while with the books to hand), but there's always the chance I'll find something new. This specimen is the Common Pug, which - strangely - I hadn't seen before:

Common Pug - Eupithecia vulgata vulgata
This moth is normally found from May onwards, so we're still a little early. It feeds on many broad-leaf plants as a larva. New to my Species List.

So that's four new species in a couple of days.

Sunday, 22 April 2012

Three for the price of one

As part of the research that I'm currently carrying out on the eggs and larvae from Soft Rush (click here for a recap), I continue to examine specimens in quite a bit of detail. Yesterday I found what is clearly a minute leafhopper covered with a fine white web:

Frog Hopper on Juncus
My mind immediately leapt to an Entomophthora-type fungus that has killed the leafhopper. A bit of research shows that there is a single fungus - Entomophthora petchii - that kills various members of this huge family of bugs, but at this stage I had no idea which leafhopper I was looking at, or even which stage of the lifecycle it had reached when it was killed (nymph? adult?). A few features need examination: those dotted wing covers seem to be small and incompletely formed. This could suggest a nymph - since bugs all go through various nymph stages (instars) before reaching adulthood, or it might be one of the brachypterous species, where specimens can reach adulthood with either incomplete wings or fully winged. Size is also an issue: this hopper is only 4mm from nose to tail.

I took shots from various angles:

Frog Hopper on Juncus
And eventually found Conomelus anceps on the brilliant UK bugs website:  http://www.britishbugs.org.uk It turns out this is a Juncus feeder, and is quite common, but I've never seen it before, so that's one new species for me. I had also never previously identified the bug-killing fungus Entomophthora petchii, although I've certainly seen leafhoppers killed by a fungus. So that's two new species for my list.

I then decided to check previous records of Entomophthora petchii and found that there are only four existing records in the BI fungal database: all from Yorkshire (Helmsley, Pocklington, Leeds, Holmfirth) (and recorded under Zoophthora petchii), so I have moved the distribution map for this species quite some way to the west. First Irish record.

So one sample has led to three new records: two for my species list and one for Ireland:
Conomelus anceps killed by Entomophthora petchii on Juncus effusus

March and April have both been very variable in terms of weather, with very hot sunshine interspersed with long periods of rain or hail. The early heat has brought out various hoverflies much earlier than usual: this is Helophilus pendulus, which I regard as a summer species:

Helophilus pendulus

And this is a Syrphus:

Syrphus sp. hoverfly
The standard reference says "April onwards", for these two species, but I've certainly never seen them this early.

Post edited to tighten up naming (leafhopper).

Tuesday, 17 April 2012

Having mentioned in my last post that St. Marks Flies (Bibio sp.) are out, I got this shot of a male this morning:

St. Mark's Fly - Bibio marci (male)
We can tell it's a male by the large eyes, which meet in the middle. In Bibios, like many other flies, the male has much larger eyes than the female, and often emerges earlier in order to establish his territory. Bibo larvae are root-feeders on many plants, especially grasses. St Mark's day is 25th April, and the flies get their name from the fact that they usually emerge around that date. I've been seeing them for about a week, so the year is still rather early. Bibios are large flies that fly around in large groups - almost swarms - often with their rear legs hanging downwards.

When I was checking the images, I noticed that I had a decent shot of a couple of interesting features:

Bibio marci head (close-up)
Firstly, we can see how hairy the eyes are. Interestingly enough, the hairs don't interfere with the fly's vision: an insect's compound eyes are made up of tubes with sensors at the inner end and a lens at the outer end. These lenses are all arranged on a curved surface, which makes them all point in slightly different directions, which is good for all-round vision. The hairs grow parallel to the tubes, and as a result have minimal impact on the vision, since the line of sight is along the hairs, not across them. These large eyes are used for navigation and for identification of mates, prey and food.

Secondly, we can see the triangle of three ocelli (auxiliary eyes, arrowed) which react very quickly to changes in light intensity, and are used to detect quick motion in order to avoid predators.

A few years ago I took a series of 'bug's-eye' views of plants. Here's a view of a Dandelion seed clock from an unusual perspective:

Dandelion seedhead
 I rather like that shot.

A few of our hoverflies have grey abdominal bands rather than the usual yellow. This is a female Platycheirus albimanus feeding on Dandelion:

Platycheirus albimanus (female)
This is by far the most common species of hoverfly in my garden at the moment.

Sunday, 15 April 2012

Sun's back

After a couple of weeks of rain, sleet and hail, things have warmed up again. Various Solitary Bees have been nectaring, and I spotted my favourite bee - Andrena cineraria - as she gathered pollen from a Dandelion:

The solitary bee Andrena cineraria
I always think they look like they're wearing Barbarians rugby jerseys. Here's a side shot:

Andrena cineraria
Andrenas (and other families of Solitary Bees) lay eggs in their own nesting tunnels, and although they might form communal 'villages' of individual nests, the female feeds only her own larvae with pollen. Nomada sp. Cuckoo Bees are ever present near the nests, hoping to get an opportunity to nip in and steal the pollen store when the female is out foraging.

Bilberry (locally called Mulberry) has flowered:

Bilberry flowers
Bilberry is a vital food source for a number of insects, most notably the Green Hairstreak butterfly. I like the way the unopened flower can sometimes contain water droplets:

Unopened Bilberry flowers
I have a number of different species of Fumitory on my patch. This is Common Fumitory, which gets its name from the grey-green foliage which can look a little smoky:

Common Fumitory

The local Willows are all in full leaf now, so it's time for the various Willow Leaf Beetles (Chrysomelids) to appear. This is Lochmaea caprea, which I happened to spot as it sunbathed on my recycling bin (which happens to be right under a Willow):

Willow Leaf Beetle - Lochmaea caprea

The Willow leaves will soon be showing the attentions of the beetle larvae as they eat off the top surface of the leaves.

I also spotted a few Bibio sp. (St. Marks Flies), which usually emerge around St. Mark's day (April 25th), so we're still running slightly ahead of schedule this year despite the last two cold weeks.