Thursday, 29 March 2012

A mystery

I was peeling a stem of Soft Rush (as one does) yesterday, and spotted what looked like a caterpillar with an orange head and a green tail inside the pith:

Juncus stem and 'caterpillar'
(For scale, the Juncus rush is about 3mm. in diameter.)

But when I examined 'it' under a lens, I found I had a collection of separate 'things' all lying adjacent to each other:

Juncus stem with 15 separate 'things'
I immediately thought of the micromoth Coleophora alticolella, which feeds on Juncus flowers, and thought that these might be the overwintering eggs, so I fired the picture off to a couple of experts (isn't the internet wonderful?) for their opinion. The consensus is that these aren't micromoth eggs, but the overwintering eonymphs of Juncus-mining sawflies.

I have mentioned before that sawflies have an 'interesting' development lifecycle and these are a prime example of that. Whereas butterflies and moths go through a strict egg-larva-pupa-adult lifecycle, sawflies can exist in a range of states including some intermediate nymph stages like we see here.

Now we notice a few things about the photograph:

1) we have three different colours: orange, white and green (very patriotic, for an Irish specimen)

2) the white ones have a brown dot on them

3) the brown dots appear in different places, but overall they describe a smooth(ish) arc.

Until something emerges (or a range of somethings emerge) from these cocoons, we can only speculate about what we actually have here:

  • It could be that the coloured specimens are about to emerge, or that they have failed and are dead.
  • The arc of brown dots could be the eyes of the eonymphs, or they could be the eggs of a parasitic wasp.

I have fired the images off to a specialist group who are experts on sawflies and I am currently waiting to see what they have to say. I could separate some of the cocoons and put them under a microscope, but I'm very keen to leave them intact to see what emerges, so I have put the sample into a sealed tube and hope to be able to identify the adults after they emerge.

I have searched the internet and can find no images of the eonymphs of likely species, so this might well be the first image of its kind.

It's only March and already we have mysteries.

Monday, 26 March 2012

Still sunny

In this extended period of sunshine, most wildlife has advanced, regardless of the fact that we're still in March. I could see five Small Tortoiseshell butterflies at the same time in my garden yesterday, and that's more than I usually see in a year. Small Tortoiseshells hibernate as adults, so I think the mild winter has allowed a higher proportion of them to survive.

Some plants are flowering at roughly the usual time: I found Germander Speedwell:

Germander Speedwell
Wood Sorrel:

Wood Sorrel
And Common Dog Violet:

Viola riviniana - Common Dog Violet
But this flowering specimen of Herb Bennet is by far the earliest I have ever seen:

Herb Bennet

Field Horsetail is a bit unusual, in that it has early fruiting growths before the sterile green parts are seen:

Field Horsetail - fruiting growth
Again, these are a couple of weeks earlier than I would expect.

If have a microscope, I urge you to put one of those fertile cones on a slide and wait a couple of days for the spores to drop. The spores are fascinating: they have four curled 'legs' which expand and contract with humidity. As they curl and uncurl, they catch onto plant parts and debris, pulling themselves along in order to aid dispersal. This is a plant with 'walking' spores.

Even the uncurling fronds of Hartstongue Fern appear to be earlier than usual:

Hartstongue fern frond uncurling
As soon as the relevant plants are flowering, then their dependant insects appear as well. This is a new moth for me - Mottled Grey:

Mottled Grey moth
The Mottled Grey overwinters as a pupa and feeds on a number of Bedstraws, but the foodplant in my locality will almost certainly be Cleavers.

The Common Quaker feeds on Willow catkins, so March is the normal time to see them:

Common Quaker moth
I spotted a horde of Gerris lacustris Pond Skaters skimming over the surface of the stream beside the path:
Gerris lacustris Pond Skaters
These detect any unfortunate insects that have fallen into the water by sensing the vibrations in the water surface: they move instantly to the precise location in a feeding frenzy that lasts just a short while.

I think I have a new favourite picture. This is portrait of a female Platychierus albimanus hoverfly:

Female Platychierus albimanus hoverfly
I particularly like the way she is highlighted by the petals of the Celandine.

I wasn't too happy with the distance shot of the Small Tortoiseshell butterfly in my previous post, so I'm showing this closeup from yesterday:

Small Tortoiseshell butterfly

Thursday, 22 March 2012

More like summer than spring

We've had an extended dry spell and the days have been bright and sunny, encouraging some species out long before I'd expect to see them.

Moths are on schedule, including March Moth:

March Moth (male)
And Clouded Drab:

Clouded Drab
It seems that this specimen has been reading the books for a change, because it is a perfect match for one of the images in the standard reference. All of my previous photographs show specimens that look nothing like the reference images.

Both of these moths are feeders on Willow catkins as an adult, and feed on a wide range of broad-leaf plants as a larva.

The Ptychopterid fly Ptychoptera contaminata is regarded as a summer species, (my previous records are from June and September) but our lunchtime temperature of 15 degrees brought this one out today:

Ptychoptera contaminata
For some reason, this species hasn't reached my species index, so that's another new species for my total (now 1415 species).

Today also brought out my first specimen of Small Tortoiseshell butterfly:

Small Tortoiseshell
These hibernate as adults and usually emerge in March or April to breed the summer generation. Small Tortoiseshells are entirely dependent on Nettles for larval food.

I spotted this early instar of the Garden Tiger moth caterpillar wandering across a path. The image shows a few of the long white hairs which will become a feature in later instars.

Larva of Garden Tiger moth 
A fine set of specimens for a mid-March spring day.

I was on the road quite a bit today and noticed a Sycamore and Horse Chestnut in leaf, a couple of 'white' butterflies flying over verges and Cow Parsley and Sow Thistles in flower. What an amazing spring.

Sunday, 18 March 2012

A sunny day

Yesterday (Saturday) was bright and sunny, bringing out many hoverflies and bumblebees from hibernation.

The first hoverfly to pose for me in 2012 was this female Eristalis tenax:

Female Eristalis tenax
There are a couple of interesting points about that shot:

  • Notice the very dark abdomen, virtually all black. The orange stripes are virtually invisible, which is due to the colder temperature during winter. These females overwinter as adults, and their offspring will have the benefit of warmer summer temperatures and will mostly have the 'normal' orange stripes.
  • I noticed that the 'Eristalis bulge' in the wing vein (arrowed) showed up well in the photograph. This is a very useful feature to learn when identifying hoverflies.

This shot of the face shows the wide vertical black stripe between the eyes, which is a strong indicator for E. tenax (other species of Eristalis have narrower stripes or no stripe):

Female Eristalis tenax - front view

Now that the Willow has catkins, the early moths are taking advantage of this vital food source. This is the (male) Early Thorn moth:

Male Early Thorn moth
This is one of the few moths that hold their wings vertically, rather like many butterflies do. (The heavily feathered antennae are the clue that it's a male).

Sunday, 11 March 2012


Willow is always the first tree to show new leaves around here, and it's a sure sign that spring growth is moving:

Willow leaves
As soon as the catkins open up, we find bees, flies and hoverflies eager to feed on the new year's food supplies:

Willow catkins
Now we can expect to see the willow-feeding Andrena bees and various Quaker moths.

Earlier today, I found my first hoverfly of the year - Eristalis tenax, and I saw a queen Bombus terrestris checking out little holes and hollows to find a place for her nest.

Many other shrubs and plants are putting up new growth as the days lengthen. This is Bramble:

New Bramble growth
And moths are to be expected, now that nectar and pollen are available from the willow trees This is the Hebrew Character, named after the dark marks at the outer edges of the forewings:

Hebrew Character moth

Sunday, 4 March 2012

Usual suspects and others

We've had around 6 days of wonderful spring sunshine, and suddenly everything is moving. I would expect to see Primroses:

 And Opposite-leaved Golden Saxifrage:

Opposite-leaved Golden Saxifrage
But a 7-spot Ladybird was a pleasant find:

7 spot ladybird
The leaves of new season's Cow Parsley have been developing for a few weeks, and already the parasitic rust Puccinia chaerophylli has appeared:

Cow Parsley, with Puccinia chaerophylli rust

And a new species of micromoth for me:

Agonopterix sp. micromoth
I know it's new to me, but sadly I don't know exactly which species it is. It's either Agonopterix heracliana (90% chance) or Agonopterix ciliella (10%), but sadly I didn't know to catch it to examine the separating features. A new species to me either way. Both are Umbellifer feeders.