Tuesday, 26 June 2012

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.


Gill said...

Interesting (as always) - do the larvae of the S. pyrastri feed directly on the aphids?

That's a super shot of the small heath which is, as you say, a lovely little butterfly.

Stuart said...

Gill, yes, the larvae are carnivorous and eat the aphids in vast quantities. Many hoverflies are aphid-eaters, which adds greatly to their value as one of our major pollinators. I have observed Syrphus sp. larvae eating aphids (and posted a few shots of them in action). Aphids give off an alarm chemical when they have been captured, so the hoverfly larvae physically lift the aphids into the air and consume them there in order to minimise the chances that other aphids will flee.

I rather suspect that the Small Heath had just emerged, because it was very docile (very unusual) and there isn't a hair out of place. Incredibly pretty, and I'm delighted to have them on my patch after years of wishing.

Denise said...

Hello there, just saw your write-up on Nature Magazine and thought I would pop on over. So glad I did, I think your photos and knowledge about your subject are brilliant!

Stuart said...

Denise, welcome to the blog. I'll mention the Nature magazine interview (and give a link) in the next post.