Warming up

It was 15C today (that's 59F in old money), so I was quite hopeful that I might find some activity. A loud buzzing led me to a queen Bombus lucorum that was scanning that back wall of a ditch, looking for a nesting spot:

Queen Bombus lucorum searching for a nesting spot

I had already seen a queen B. terrestris earlier in the week, but couldn't get a shot, since they move pretty quickly. I would certainly expect to see B. terrestris a lot earlier than B. lucorum, so this one was a bit of a surprise. I also saw another B. terrestris in my garden late yesterday afternoon, so they're clearly out and about.

Now that I'm doing the 1k square challenge, I'm looking even more closely at everything. I noticed that a specimen of Soft Shield Fern had some brown blotches on the upper surface and suspected that something was going on. I turned the frond over and found the feeding signs and pupal case of the micromoth Psychoides filicivora:

Larval case of Psychoides filicivora (centre)

The larva eats the sori (spore-bearing containers), leaving the distinctive brown blotches (to the right and top of the image) and then makes a shelter (centre) where it pupates. The adult emerges in May. Psychoides filicivora was discovered in Dublin in 1909, and has now spread throughout the island. It is thought to have arrived on ferns brought in from other countries, and has now been found in coastal areas in England and Wales. The literature states that it is known from Soft Shield Fern, Male Fern and Hartstongue Fern, but in Ireland it can also frequently be found on Polypodium. I examined a few fronds and, sure enough, I found this specimen: 

Psychoides filicivora on Polypody

I'll have to inform the references to get them updated.

A couple of flowers have opened in the last week:

Primrose, which is probably 2-3 weeks behind the usual schedule:

Primroses

And Coltsfoot which is at least a month late in flowering:

Coltsfoot

Coltsfoot is a little unusual, in that the flowers appear before the leaves. That means that the energy used to produce the flowers comes from last year's growth, and must be stored in the root system. There must be a good reason for that odd behaviour, but I can't immediately think of a beneficial one.

The 1k challenge has now reached 258 species. You can see the list here.

Serendipity

My photography sessions are dominated mostly by the weather, and even when the weather is half-reasonable I can still struggle to get half a dozen decent shots. Sometimes, however, everything clicks and I manage to get a good range of illustrative images.

Scaeva pyrastri is a hoverfly that can be readily identified by the abdominal markings: they are paler than most species and the inner part of the curve is further forward than the outer part. In this shot, you can also see the hairy eyes, which separate it from other similar species.

Scaeva pyrastri hoverfly

Scaeva pyrastri is thought to be immigrant from mainland Europe, and I know that there has been a mass migration of moths to Ireland in the past couple of days, so this hoverfly has almost certainly flown from France to breed here. (The brown hoverfly at top left is Eristalis pertinax).

Eristalis intricarius is one of our best bumblebee-mimicking hoverflies:

The bumblebee mimicking hoverfly Eristalis intricarius

That yellow/orange 'band' is very convincing in life, but when you see it close-up, it's clearly just a scutellum with longer than usual hairs.

And just as I was standing up from taking that shot, I saw the very bumblebee that it is mimicking:

Bombus lucorum (agg) (right) and Bombus pascuorum (left, both workers)

That's a nice shot of two of my 6 local bumblebee species.

Helophilus pendulus is perhaps the most common single species of hoverfly on the patch at the moment. I know that there are a few related (but rarer) species that might be around, so I examine each specimen very carefully just in case. Today I got that 'eureka' moment as I found this male Helophilus hybridus:

Helophilus hybridus (male)

Helophilus hybridus larvae are associated with black mud where Bulrush is present, and the adults don't disperse very far. There is a stand of Bulrush about 300m. from where this shot was taken.

Here's an archive shot of Helophilus pendulus for comparison:

Helophilus pendulus (archive)

Notice that the yellow abdominal markings are quite different, and the rear legs are yellow only at the 'knee' in hybridus, but the yellow is extensive on pendulus.

The larvae of some fly and micromoth species feed on the seeds of composite flowers such as Knapweed. The seeds are an excellent food source, and the larvae can feed inside the undeveloped seedheads in relative safety.

Notice the word 'relative'; some parasitic wasps are aware that there are larvae inside the flowerhead, and at the appropriate time (now) we can see the Ichneumonids searching the unopened flowerheads. When a larva is detected, the ovipositor is deployed and we see the drilling operation that takes place:

Ichneumonid ovipositing in larvae inside the Knapweed flowerhead

The eggs are deposited inside the body of the hidden larva and will remain there until the larva has reached full size. At this time (or soon after the larva has pupated) the ichneumonid egg hatches out and the ichneumonid larva eats the host before pupating inside the husk. This egg-laying process can be seen in perhaps three days per year.

Here's an unusual shot of the process from the rear:

Ichneumonid ovipositing

A few days ago, I showed a picture of a very atypical Square-spot Rustic. Here's one that looks as if it has read the book and followed the rules:

Square-spot Rustic

Here's a link to the original post, for comparison.

Gap in the clouds

An unexpected gap in the clouds prompted me to visit our highest local point in search of orchids.

Northern Marsh Orchid is the first of our local Dactylorhiza orchids to open:

Northern Marsh Orchid

All of the Dactylorhiza orchids freely hybridise with each other in a fertile manner, so I always like to assign a percentage of the three local 'species' which appear in any specimen. The first specimen, above, is very close to the 'clean' specification, (short spike, dark flowers, clean edge to lip of flower) so it is mostly Northern Marsh orchid.

The next specimen is paler and has a slight tooth to the front edge of the lip, so I'll give it 90% Marsh and 10% Common:

Northern Marsh Orchid with signs of Common Spotted Orchid

This third specimen is clearly a hybrid with Common Spotted Orchid (tall spike, still paler flowers, visibly sharp tooth):

Northern Marsh Orchid x Common Spotted Orchid

I'm pretty sure that third one has some Heath Spotted Orchid in it too.

Interestingly enough, the hybrids tend to follow the flowering dates of their major partner: Northern Marsh Orchid is always around 3 weeks earlier than Common Spotted or Heath Spotted, with hybrids somewhere in between, so it's not only physical characteristics that are shared. My 'clean' Spotted orchids are only starting to make spikes now.

I was astonished to also find a Common Twayblade orchid in this location:

Common Twayblade

I strongly associate Common Twayblade with limestone, so the road in this area must have been fortified or built with limestone chips, since this location is in a strongly acidic heath area. We need to be alert to just how much our actions can affect populations of plants (and hence insects).

Staying with the theme of habitat alteration, this part of the heath has become overrun with False Salmonberry:

False Salmonberry

False Salmonberry is an american rubus species that was introduced in Northern Ireland to support game birds for shooting. I first saw it locally about 5 or 6 years ago as isolated specimens, but now it has covered acres of heath, eliminating native species as it spreads. It is clear that this is yet another highly mobile and invasive plant.

Bumblebees that are brighter than usual tend to be males, especially if they have yellow hair where black would be expected.

Male Bombus lucorum

The tuft of yellow hair on its 'nose' is a clear indicator, but the overall colouring (in association with the absence of pollen bags from the hind legs) leaves little doubt. The flower is Common Catsear.

The hoverfly Sericomyia silentis is an excellent wasp mimic:

Sericomyia silentis hoverfly

It's quite a common hoverfly, but I rarely see it in large numbers.

Double delay

After a wonderful April, it has rained every day in May so far, sometimes very heavily. Blogger has also been offline for a few days, so I have a bit of catching up to do.

Worker Bumblebees are very numerous now, although most of the current ones are from the queen's first batch of eggs and are therefore very small. The ones gathering pollen from Raspberry flowers are scarcely larger than a pea:

Worker Bombus lucorum agg.

Hawthorns are in full flower now, and in keeping with the trend this year are bearing many more flowers than usual. Some trees are almost entirely white (and some are almost entirely pink!). The fresh flowers have pink interiors, but that very quickly disappears, leaving a much duller flower:

Hawthorn blossom - "May"

Hawthorn blossom is known as 'May', and is the origin of the northern saying: "Ne'er cast a clout e'er the May is out". Which translates to "Don't divest yourself of warming clothing until the Hawthorn has flowered".

The hoverfly Cheilosia grossa feeds on Thistles as a larva. The larvae can be detected by their effect on the host plant: any thistle that branches from ground level and appears dwarfed can be considered to be potentially 'occupied':

Male Cheilosia grossa

I already showed the first of the Orange Tip butterfly eggs here. The female lays a single egg behind the flower, waiting for the seedpod to develop. She lays only one egg because the larvae are cannibals: any young larva will be consumed by an older one. In the early season, I only ever find a single egg per plant: females detect the presence of an existing egg and will move on to other suitable plants to lay their eggs. At the end of the season, however, all the suitable plants already have eggs and I find what I call the "Let's dump eggs on all the plants in case one might just actually make it" syndrome. This photo shows at least 14 eggs on one plant:

Orange Tip eggs and larva

And top of the class to anyone who spotted the first Orange Tip larva on the seedpod at the front of the picture.

The important thing to realise here is that synchronisation is crucial: if you emerge before the host plant is ready, you will have nowhere to lay your eggs. If you emerge too late, then all the suitable (southwest to south-facing plants on an embankment to catch the sun) plants will already be occupied and your late larvae will have to hope that they don't encounter one of the early occupiers. The window of opportunity is perhaps 14 days. This theme of critical synchronisation occurs time and time again in our wildlife.

The next shot illustrates one of the most stunning aspects of our natural history:

Female Dungfly infected with Entomophthora muscae fungus

The image shows a female Dungfly that has been killed by a fungal infection. The fungus Entomophthora muscae enters the digestive tract and progresses to the abdomen where it multiplies and expands. As it expands, the pink mass begins to break through the abdominal segments as shown above. But now we come to the crucial bit of the exercise: before the fungus kills the fly, it compels the fly to climb towards a high point and then to open her wings. Then it kills her. This combination of high position and open wings affords the maximum opportunity for wind-borne spore distribution for the fungus. So the fungus gains control of the movement of the fly in order to maximise the opportunity for dispersal of its spores.

Keep learning

Over the years, as experience builds up, you make a series of 'rules' which help you reach an identification. Until yesterday, one of my rules was "If you see a bee which is less than 20mm long, then it isn't one of the social bees". Applying this rule, I leaned towards one of the Andrena solitary bees for this specimen: 

But it didn't match any of the images that I could find in the usual places. When I asked for help, back came "It's a Honeybee". Blinded by assumption (and not helped by the fact that this was roughly 60% - 70% as big as I would normally see), I had excluded the obvious. Factor in the fact that Honeybees have become very rare in our area, and the mistake is easy to make.

Assume nothing.

Moving swiftly on......

This Eristalis tenax hoverfly has the very dark colouring that we expect to see in early specimens. The summer generation of many of our hoverflies is much brighter due to the higher temperatures. This female will have mated at the end of last year and has managed to successfully shelter in some nook or cranny through the -17 degrees that we endured in December:

Female Eristalis tenax

The Willow catkins opened last Thursday (17th) and insects have been busy nectaring and gathering pollen ever since. This queen Bombus lucorum bumblebee found the pollen quickly enough:

Queen Bombus lucorum

She is now gathering enough pollen to feed the first few workers from her nest, and she will spend the rest of the year laying more eggs to sustain the nest and produce drones and queens for next year's generation. A few of the new queens actually become workers for a while at the end of the season, gathering pollen alongside the last of the workers.

With the early willow pollen season being so short, no time is wasted before the willow-dependent moths appear. This is the first Common Quaker - Orthosia cerasi - of the year:

Common Quaker - Orthosia cerasi

The Common Quaker is readily identified by the large, rounded, 'kidney mark' which has a pale, thin, outline which matches the colour of the thick band near the trailing edge of the wing. 

Busy time

The burst of good weather has produced lots of new photographs (which bring associated research), and I have been working on a new project doing wildlife surveys with schools in the area, so things are a little busy.

The leafmining fly Agromyza minuscula mines Meadow Rue as well as the Aquilegia in my garden. I have no Meadow Rue near my patch - it tends to be coastal near here - so the flies have travelled quite some distance to find this alternative food source.

Foxgloves tend to creep up on you. One day, they're a rosette of leaves, the next they're in full bloom the whole length of the spike:

Last week, I showed a male Bombus lucorum; this one has found a new queen:

I'm amazed at the size difference. The males will now die off, and the new queens will go back to their nests and act as workers until next year when they go off to make their own new nest. The queen is certainly Bombus Lucorum s-s, which confirms my belief that I have both B. lucorum s-s and Bombus cryptarum on my patch.

Meadow Vetchling has added a lot of yellow to the verges, now. The various Cinquefoils are next, followed by various St. John's Worts and the Birds-foot Trefoil.

I often think the people who gave names to various species in the 1700's and 1800's had a sense of humour (or they needed some light relief from their intense work). This is the wasp-mimicking hoverfly Sericomyia silentis, which has to be the noisiest hoverfly around. It's certainly louder than the bumblebee:

There are plenty of moths around at the moment (sorry, Weaver). This is a male Golden Swift:

I did quite a bit of research on this image because I have often seen these bright orange phoretic mites, and always on Limoniidae Crane Flies:

Limoniidae are often aquatic as larvae, but some feed on fungi. These phoretic mites are also known to feed on fungal spores, so it looks like these mites (which belong to the spider family) are simply using the Limoniidae as transport between fungi.

Finally, some more moths that came to light:

Clouded-bordered Brindle - Apamea crenata - which feeds on grasses as a larva:
Common Marbled Carpet - Chloroclysta truncata - which feeds on woody plants:
And Dark Arches - Apamea monoglypha - another grass feeder:
New to me.

I also updated my species index.