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.

Opportunistic shots

The weather has continued to be cold or dull or wet, or all three at the same time, but I suppose it isn't only us this year.

Scaeva pyrastri is thought to be a migrant hoverfly - at least for the first generation - in Ireland, but I suspect that as we get warmer, then it might well join the growing list of insects that have become winter-resident, like the Red Admiral butterfly, for example. I was just saying the other day that when I was younger, books seemed to have facts in them, nowadays they seem to contain mere guidelines, because so much is changing so quickly.

I spotted this female Scaeva pyrastri hoverfly as she examined each flower stem and seedhead for aphids:

Female Scaeva pyrastri hoverfly ovipositing

Every so often she would stop and lay an egg in amongst any aphids she spotted.

I checked one batch of aphids after she had moved on, and sure enough, I could see the egg - apparently directly on top of an aphid - arrowed in this shot:

Scaeva pyrastri egg (arrowed)

Male hoverflies are known to hover for a variety of reasons, such as protecting territory or showing off their skills to attract a mate, but this female was hovering very accurately as she minutely examined the flower stems and seedheads from around 10mm away. The Small Heath butterfly is very particular about its habitat: it likes heathy areas with shorter grass, but I'm sure it has some other requirement that we don't know about, because many apparently suitable habitats are ignored by them. I had always thought that one particular area on my patch was suitable, but it was only after 8 years of searching that I found a single specimen there last year. A couple of sightings at the same location this year - including the one in the shot - suggests that a colony has now been established:

Small Heath butterfly

It's a lovely little butterfly, and a welcome addition to my local list.

Syritta pipiens is readily recognised by the inflated thighs on the rear legs:

The hoverfly Syritta pipiens, female

A few moths have been brave enough to beat the rain, although reports of populations are far lower than normal, sometimes as low as 10% of the expected numbers. The Hawkmoths are our most stunning moths, and I was fortunate that this Poplar Hawkmoth came to light:

Poplar Hawkmoth

These are as large as smaller bats, and on a 17" screen at 1024 x 768, that picture isn't much larger than life size. The Poplar Hawkmoth larva usually feeds on Poplar, but hereabouts it will be Willow. Notice that the wings of this species at rest are held in a very unusual configuration, with the rear wings ahead of the front wings.

The Common White Wave is a handsome little moth:

Common White Wave moth

This species is distinguished from the Common Wave by the almost-straight rear grey lines on the forewing.

This weevil caused me a bit of pain during the identification process. Most web references say that it is associated with Dog's Mercury, which doesn't grow around here. It keyed quite quickly to Barynotus moerens, but with all the web references stating that it was associated with a single plant, I retried the identification several times to see where I had gone wrong. 

The weevil Barynotus moerens

After much angst, I found that it is also associated with Ground Ivy, which we have in abundance around the patch. I think many websites (and some reference books) just copy what they read elsewhere without examining the facts.

New to my species list.

High pressure migrants

Yesterday I showed the first specimen of the hoverfly Eupeodes luniger for this year, and today I saw a lot more. The hoverfly Scaeva pyrastri is known to be migratory and I saw it on the marigolds today:

So I rather think the south-easterly wind that accompanied the current high-pressure weather system has brought in a mass migratory influx from mainland Europe.

I also saw my first 2010 specimen of the parasitic tachinid fly Eriothrix rufomaculata:

I only ever see this on Ragwort. Its host caterpillar is unknown in Ireland, and I'm beginning to wonder if it's migratory, too. I need to sit and think if a migratory parasite makes sense.

Woody Nightshade is a plant that seems threatening in all of its parts:

Maybe it's the purple stalks near the flowers and fruit, but I can certainly see why our ancestors viewed early tomatoes with more than a hint of suspicion.

A collection from gaps in the rain

Another Dolichovespula sylvestris, but this time I think it's a male. Angelica is great for insects.


This Ichneumonid with huge antennae was wandering over leaves, sweeping the antennae from side to side. Long antennae usually indicate the male, but I'm sure this one was searching for larvae on the underside of the leaf.



Two shots of one of my favourite hoverflies, Scaeva pyrastri:


And a good wasp mimic, Sericomyia silentis.


Most leafminers make either a gallery mine (long and thin) or a blotch mine (erm, blotchy). Agromyza sulfuriceps does both. The mine starts as a gallery, then the gallery twists are all made adjacent to each other. Finally it breaks the walls and makes the blotch. A blotch mine has a distinct advantage in that the upper surface of the leaf can be pushed upwards. This allows the larva to grow bigger due to the increased space. So maybe this is a once-little fly that's getting bigger.


I have to leave the identification of this one a bit abstract: the species complex hasn't been fully worked out, yet. So it's Chromatomyia sp. On Common Ragwort.


As I was walking back to the car I heard a Buzzard high above me. No telephoto on a macro lens.

Migrant hoverfly?

The hoverfly Scaeva pyrastri is thought to be migrant in Ireland, so this female has come a long way. (The justification for it being a migrant is based on the late appearance of this species in Ireland.)


She was exploring the various flowers in my garden and I noticed her taking special interest in (and subsequently ovipositing on) those with aphids:



A quick check of the references revealed that Scaeva pyrastri is, indeed, predatory on aphids, so I'll try to get some shots of the larva in the next week or so.