Thursday, 27 June 2013

High Heath

The Green-veined White butterfly has two generations per year. Unusually, the two generations are quite close, with some slight degree of overlap. Summer generation specimens are more strongly marked, with the black markings being darker and sharper than those of the spring generation.

 This pristine specimen is a female:

Female Green-veined White, summer generation
Given the lateness of the year, this is a rather early specimen for the second generation.

I have found the same, strange, earliness in the bumblebees this year. Queens emerged rather late, and nests were subsequently late, with workers not appearing until a few weeks ago. There is usually quite a delay until the new queens and males are ejected, but I have been seeing new queens and males for a couple of weeks now: much earlier than usual. It seems that some species are actually accelerating this year, despite the slow start, and are now ahead of normal schedule, rather than maintaining the 'lateness'.

Male bumblebees are ejected from the nest to fend for themselves, mainly because they do no work and would be an overhead on the nest. They are quite easy to identify, both in behaviour and appearance: they tend to crawl slowly over flowerheads in contrast with the workers which gather pollen almost frantically. They are also rounder, more colourful and have longer hair, giving them a 'fuzzy' appearance:

Male Bumblebee on Common Catsear
Any bumblebee with yellow hair on its face is likely to be a male, although not all males show this feature:
Male Bumblebee showing yellow hairs on the face
It isn't possible to identify these males to species without internal examination, but given the location, I'd go for Bombus lucorum s-s.

The hoverfly Helophilus pendulus is very numerous at the moment, with sightings on every excursion and location.

The hoverfly Helophilus pendulus

But I still examine every specimen, since I know that the much more local Helophilus hybridus can occasionally be found:

The hoverfly Helophilus hybridus
These rarely fly more than a few hundred metres from the boggy areas that contain Bulrush - the foodplant of their larvae. Identification relies on the differences between the markings on the abdomen. I might see only one or two of these each year.

The hoverfly Platycheirus scutatus was split into 4 species quite recently. Irish specimens appear to be the original Platycheirus scutatus s-s.

Platycheirus scutatus, female

Platycheirus scutatus, female
The larvae of these feed on aphids on low-growing vegetation.

Digger wasps can often be mistaken for hoverflies due to the oval yellow markings on the abdomen, the large head and the apparently short antennae: all features of hoverflies. These are predators on hoverflies, killing them and taking them back to the nest to feed their larvae:

Ectemnius continuus
Their appearance enables them to mix with hoverflies and approach them without disturbing them: I have often seen hoverflies and Ectemnius wasps feeding on the same flowerheads.

Hoverflies mimic the colour patterns of wasps and bees with greater or lesser accuracy. This enables them to inherit the protection that the colour patterns give to bees and wasps: birds know to avoid yellow and black -  nature's danger signal. So Ectemnius wasps are imitating hoverflies that are imitating wasps.

Staying with mimicry, Volucella bombylans is a hoverfly that mimics bumblebees (and lays its eggs in bumblebee nests):

The bumblebee-mimicking hoverfly Volucella bombylans
Volucella bombylans comes in at least three colour versions, each mimicking different bumblebees. I would dearly like to know if the different versions choose appropriate bumblebee hosts to rear their young.

Sawflies are very difficult to identify to species without a specimen, a microscope and a key. I have recently obtained a copy of the (55 year-old!) key and have identified this specimen as Tenthredo mesomelas:

The sawfly Tenthredo mesomelas
In an effort to understand these adults and larvae, I am participating in an online effort to gather together images of both adults and larvae of all sawfly species together for the first time.

When I was down taking photographs of orchids (see here), this micromoth flew over my head and landed on the Luzula upside-down, as so often happens.

The micromoth Glyphipterix thrassonella
The larvae of Glyphipterix thrassonella feed on Juncus rushes, which were in profusion. This is the first time I have seen this species since 2005.

Meadowsweet must be a very nutritious plant: there are many miners, micromoths and fungi which use it as a host. This is the fungal rust Triphragmium ulmariae, which is specific to Meadowsweet:
Triphragmium ulmariae on Meadowsweet
Note that the fungus has distorted the stem of the plant in order to maximise its surface area and therefore increase its chance of spore-dispersal.

And this is the mine of  Agromyza filipendulae on the same plant:

Unusually-shaped mine of Agromyza filipendulae on Meadowsweet

Note that this particular mine is atypical: it should have continued spreading to the left, but for some reason it has turned back at the fourth vein. Perhaps it was parasitised.

3 comments:

The Weaver of Grass said...

Stuart - as usual, your photographs are exceptional. Do you publish them anywhere - they are certainly worthy of publication.

Glad you like my plates - they are called Jack's Farm and I bought them on a stall on our market - a discontinued line I think. They always make a very ordinary meal (and nothing is more ordinary than corned beef is it) look special.

stuart dunlop said...

Weaver: Thanks for that. My images are used in lots of different places: books, magazines, websites, essays, school projects, brochures, promotional pamphlets, signage, etc. I am working (on and off, when the urge takes me) on a book about wildlife which will be fully illustrated throughout with my pictures. I'm also working on watercolour skills so that I can do e.g. chapter headings with my own illustrations.

As you know, I'm particularly interested in food and cooking, and we have a number of different place settings for different occasions and international cuisines. I collect serving dishes almost as avidly as I collect cookbooks. My main large mixing bowl was bought from a stall in France and features geese and grapes on a blue background. That always gets nice comments when I'm making bread during cooking classes. I do feel that having nice things around me when I'm cooking makes the whole process more enjoyable. I also have a pile of fancy posh presentation plates from when I was doing Masterchef, but that's a whole different story.

The Weaver of Grass said...

Stuart - think you must be away as you haven't blogged lately. However, please do go to Foxglove Covert's Home Page and click on Blog - they do a moth count every Tuesday night/Wednesday morning - this week they got over 300 moths with 57 different species - they have put some of the photographs of the rarer ones on their site.
I am impressed re Master Chef - please tell.