Thursday, 31 May 2012

Catching up

The good weather has continued, which means that I'm taking hundreds of photographs. Identifications and image selection are taking up a lot of time, so I have quite a backlog.

But tonight I got a very rare opportunity to make a feature of a single species in my post, so here it is:

Ladybirds start off as eggs and then hatch into larvae that go though 3 - 4 stages (instars), shedding their skin as they grow. Their sole food is aphids, so judging by the number of larvae and pupae I found tonight, a vast number of aphids have been consumed this spring.

Early larvae of the 7-spot ladybird are dark with yellow or orange spots:

7-spot ladybird larva, early instar
The final instar larva is, however, grey:
Final instar 7-spot ladybird larva
When the larvae are fully grown and ready to pupate, they begin to curl up with the head down and the tail tucked in:

7-spot larva about to pupate
The larva then begins to change colour as it pupates:
7-spot larva during pupation
(note the yellow under-colour shining through the thin skin)

The outer skin is shed and pushed to the rear of the pupa by means of several quick thrusts of the entire body (the shed skin can clearly be seen at the rear of the pupa):

Fresh 7-spot ladybird pupa

After a short time, the pupa hardens and takes on a darker colour:

7-spot ladybird pupa

And after a few days:

Adult 7-spot Ladybird

I have never seen such a wide range of stages of one species in one place at one time. Our exceptional spring weather has clearly been beneficial to the 7-spot at least.

Friday, 25 May 2012

Under pressure

High pressure, as in sunny weather, brings out all the insects, so things have been quite busy.

The Common Carder Bumblebee - Bombus pascuorum - is the latest of my local bumblebees to establish a nest. Most of the specimens seen around are still queens stocking up their reserves before the workers emerge for the season:

Common Carder Bee on Bush Vetch

Members of the Empid family of flies are commonly called 'Dance Flies' due to their habit of forming mating clouds where individuals bounce vertically within the cloud. They are voracious predators, sucking fluids from their victims with their long proboscis. Sometimes, however, the proboscis is used to reach nectar in flowers:

Empid fly on Creeping Buttercup

Hoverflies are everywhere at the moment, which is good news: they pollinate flowers, trees and crops, so the more we see the better. Eristalis arbustorum can be separated from other Eristalis species by the lack of a dark stripe down the face in association with the swollen rear leg which is conveniently extended in this shot:

Eristalis arbustorum hoverfly

Rhingia campestris is an increasing species which used to be found mainly near farms (the larvae live in dung), but is now found in most habitats:

Rhingia campestris hoverfly
That long 'snout' contains a folded-up tongue which it unfolds to suck nectar that other insects cannot reach.

Leaf-mining species don't wait long after the leaves emerge before laying their eggs: they have to make use of their only food as soon as it's available. This is the very common Phytomyza ranunculi, which mines various members of the Buttercup family:

Phytomyza ranunculi mining Creeping Buttercup

I increased the light intensity on this shot to show the larva more clearly:
Phytomyza ranunculi close-up showing larva in mine
The mines of Phytomyza ranunculi can be separated from those of the much rarer Phytomyza ranunculivora by the pattern of 'frass' (dung droplets), which are joined up ("string of pearls") in P. ranunculi, but are quite separate in P. ranunculivora (Click here for comparison).

Most predators are adept at catching their own food, but some chance upon their next meal whilst simply wandering about. I saw this Lesser Dungfly discovering an already dead fly and after a brief inspection, it wasted no time in tucking in:

Lesser Dungfly with discovered corpse

I previously showed the newly-laid egg of the Orange-Tip butterfly. As expected, the egg has now turned orange and should hatch in the next day or two:
Orange Tip butterfly egg on Cardamine

Good weather encourages moths to emerge and they can often be seen beside lights at night: I keep one light running to see what I can attract. This is Common Marbled Carpet - a very variable moth (and this specimen is quite worn, making identification even more tricky):

Common Marbled Carpet moth

Just to show what we're up against in moth identification, here is a shot of Goldenrod Pug - Eupithecia virgaureata:

Goldenrod Pug moth
Compare that with my previous shot of the same species here. The only features in common are the (faint) elongated wing spots and the tuft of whitish scales behind the thorax. This colour variation has been named as f. nigra for fairly obvious reasons.

Lastly, a shot of the very common Buff Ermine moth. The caterpillars are very common in wooded areas and look like the business end of a stiff yard brush.

Buff Ermine moth

Sunday, 20 May 2012

Echoes of last year

The early summer this year is looking depressingly similar to last year's: good weather in March and April, but cloud and/or rain from May through to September. Having seen butterflies throughout March and April, I haven't seen a single one since the first of May.

It's not all gloom and doom, however, since warm wet weather is ideal for fungal rusts. (The microscopic analysis required to identify them is also something to do on a rainy day.)

This is the fungal rust Melampsora hypericorum on Tutsan:

Melampsora hypericorum on Tutsan
And this is Uromyces acetosae on Common Sorrel:

Uromyces acetosae on Common Sorrel
Astonishingly, this very common fungus - which has been recorded from Cornwall to the Outer Hebrides - has no previous Irish records. Must be an oversight. No previous Irish records.

Very few parasitic fungi have a common name, but Botrytis fabae (in this case on Bush Vetch) is commonly known as 'Chocolate Spot' disease:

'Chocolate-spot' on Bush Vetch
I suppose any disease that affects crops will tend to have a common name. Again, no previous records from Ireland.

Although I still haven't seen a female Orange Tip butterfly this year, they are clearly around: I found this single egg on Cardamine pratensis - their sole foodplant in this area:

Orange Tip butterfly egg on Cardamine pratensis

Ferns must be amongst our most architectural (or at least geometric) plants. We all know they unfurl lengthways, but the pinnae also unfurl widthways:

Unfurling Scaly Male fern

We have four species of horsetail on the patch. This is Water Horsetail, which usually has no branches, but can also be found in a branched version, like this one:

I keep looking for the named hybrid between Water Horsetail and Field Horsetail which are both found adjacent to each other at this location, but all specimens seem to be one or the other.

Dungflies are very numerous at the moment, sitting on leaves or hiding in flower heads. They are ferocious predators, and if you watch them for any length of time they will pounce, catch and then devour other flies and wasps. This is the male (the female is green):

Male Scathophaga stercoraria Dungfly

Many of the schools around here have an ongoing 'Green Flag' initiative which encourages children to recycle and helps them to be aware of their local biodiversity. I was invited to open and examine a log pile which had been placed in a dark corner of the playground of one local school and I got a few photographs during the analysis.

We found plenty of woodlice:

Oniscus asellus - Shiny Woodlouse

Oniscus asellus - Shiny Woodlouse

And this excellent spider, which I haven't identified yet:

Unidentified spider from log pile

We also found:

Cup mushrooms
and a Millipede

The Woodlouse and two of the fungal rusts are new to my species list, so it continues to expand despite the weather.

Saturday, 12 May 2012

Curiouser and curiouser

Two of my recent posts have shown the results of my research on eggs and insects in Juncus rushes, and a great deal of additional background research has been taking place in the interval since those posts were made. In order to keep things neat and tidy, I'll be reproducing a couple of images from those posts in the report that follows.

Firstly, on 29th March, I showed these eggs:

Leafhopper eggs in Juncus

These have been identified as leafhopper eggs, but the species is still undetermined. Two species of leafhopper are known to associate with Juncus: Cicadella viridis and Conomelus anceps.

On 22nd April, I showed this dead specimen of Conomelus anceps:

Conomelus anceps killed by Entomophthora petchii on Juncus effusus
I was able to get a very accurate description of the Conomelus eggs from the UK expert on such matters and after some exhaustive searching, I managed to find a sample of Conomelus eggs from the Juncus:

Conomelus anceps eggs in Juncus
From the scale of the image, it can be seen that these eggs are very much smaller than the original leafhopper eggs from March. It's also worth pointing out that while the original eggs are in a line of 15 eggs, the Conomelus eggs are laid in smaller batches of 4 or 5.

Cicadella viridis is a much larger leafhopper than Conomelus anceps, but it turns that although C. viridis feeds on Juncus, it lays its eggs in the bark of thin-barked trees, so the identity of the original leafhopper eggs still remains a mystery.

In more recent pursuit of the owner of the original eggs, I have found other species and other eggs. This latest set of eggs is most bizarre:

Conomelus anceps eggs (A)

Arrow 'A' shows a couple of Conomelus anceps eggs, but the multicoloured eggs are, again, in a straight line (and are larger). The varied colours and shapes of these eggs suggest that they have been parasitised - presumably by minute parasitic wasps. So I think this image shows two sets of eggs: the Conomelus eggs on the left and a parasitised row of the original eggs which still remain unidentified.

Arrow 'B' points to a particular egg which caught my attention. It seems to show a nymph of a leafhopper of some kind, so that is my current area of research. I've blown up that part of the image here:

It looks to me like a leafhopper nymph looking directly towards the camera. Time (and a great deal of further research) will tell.

Thursday, 3 May 2012

More synchronisation

Grasses can be incredibly difficult to identify, but fortunately - once the initial identification has taken place - many can be readily identified in the field. This is Meadow Foxtail - Alopecurus pratensis:

Meadow Foxtail grass

And this is Sweet Vernal Grass - Anthoxanthum odoratum, which gets its name from its sweet smell when dry, and also from the fact that it is one of the earliest grasses to flower:

Sweet Vernal grass

Of course, as soon as those fresh new leaves are available, the parasites move in. This is the rust Puccinia graminis on Meadow Foxtail:
Puccinia graminis on Meadow Foxtail grass

Now that the sun is out again, micromoths are making an appearance. This is Ancylis badiana, about 10mm long:

The micromoth Ancylis badiana

The larvae of Ancylis badiana feed on various members of the pea family, including clovers and vetches. The larvae of the following species of micromoth, however, are unknown.

Micropterix calthella is always to be found in or near Meadow Buttercup. Adults are 4mm long.

The micromoth Micropterix calthella on Meadow Buttercup
I watched this specimen as it wandered over the flower and then posed in profile. Note the wonderful yellow tuft of hair, like a wig:
Micropterix calthella close-up
Given the adult moth's predilection for Meadow Buttercup, I'd guess the larvae live on the roots of it.

As I was walking along, I felt a tickle on my arm, and I immediately thought "It's too early for midges". I rattled off a couple of shots of the microscopic beast and was delighted to find this minute (2mm) Chalcid wasp struggling through the hairs on my arm. Chalcids are tiny members of the Ichneumonid family, parasitising micromoths and other small insects. 

Chalcid wasp
Note the very sparse wing venation, which is a feature of Chalcids, and also the dark triangular pterostigma, which is a feature of ichneumonids in general.

Staying with parasitisation, I found this 'mummified' aphid on Cow Parsley. Aphids which are inflated and glossy like this have usually been parasitised by a member of the Aphidius family of Braconid wasps, which are yet another branch of the ichneumonid family:

Aphid parasitised by Aphidius sp. wasp

Ferns are all unrolling, now. This is Scaly Male fern - Dryopteris affinis:
Scaly Male fern unfurling
Ferns are a major component of the hedgerow, providing food, shelter, display and basking opportunities for many insect species.

Tuesday, 1 May 2012

Sun continues

While much of the UK has been under water for the past month, I'd hazard a guess that April was one of the driest on record in Co. Donegal. Although we've had a lot of sun, the wind has been easterly and that keeps things cooler.

Butterflies are out and about, though, and I've had Small Tortoiseshell, Speckled Wood, Green-veined White and now Orange Tip.

The male Orange Tip is unmistakeable, with those bright orange wing-tips:
Orange Tip butterfly - male
The males emerge a few days before the females in order to establish their territory, which they will defend against any moving white object, including pieces of paper. The females will be out next week and then I'll be looking for eggs on their host plant - Cardamine pratensis.

Green-veined White is usually the first of the spring-emerging butterflies on the patch. The males have fewer black markings than the females:

Male Green-veined White butterfly nectaring on Herb Robert

Male Green-veined White butterfly
Here's a shot of the female for comparison:

Female Green-veined White butterfly
Interestingly enough, the Orange Tip and Green-veined White share a common foodplant, but whereas the Orange Tip larvae eat the seedpods, the Green-veined White larvae eat the leaves.

Tachinid flies are parasitic on the caterpillars of larger moths, and are readily identified by their extremely bristly appearance:

The Tachinid fly Gymnocheta viridis
Judging by the number of Tachinids I encounter, it is clear that they are serious population controllers.

The Clouded-bordered Brindle moth is normally found from late May onwards. This is fully a month early, so the heat has brought the overwintering larvae on a bit more quickly than usual.

Clouded-bordered Brindle moth
The moth above is rather unusually marked: the central white 'kidney mark' is missing. Compare with this one from a couple of years ago.

Breaking news: the recent mystery eggs that I showed in Juncus rush appear to belong to a leafhopper, rather than a sawfly. Full details in the next post.