Hoverfly leaf-miner

Leaf-miners belong to one of 4 groups:

• Micromoths
• Flies
• Beetles (weevils)
• Sawflies

The flies are usually Agromyzid flies, which are all leaf-miners, as far as I can work out. But I found this miner on Navelwort - Umbilicus rupestris:


The list of options for that foodplant is very small (one micromoth and one fly), and this looks like a fly mine, so I'd have to opt for Cheilosia semifasciata - which is a hoverfly.

However (and this is where it gets very interesting), the other Cheilosia sp. aren't leaf-miners. Information about Cheilosia semifasciata is scant - there is no image of the adult in the standard reference - but it appears to be an oligophage: it mines plants that belong to a single family (another host plant is Orpine - Sedum telephium). So it appears that one member of a hoverfly family has independently discovered leaf-mining, and on a plant that is not mined by any other fly. Interesting.

Edit: it turns out that this hoverfly is extraordinarily rare, and I'll be monitoring the situation over the next week or so.

Art?

I usually concentrate on 'factual' images, showing species in a scientifically useful manner, but tastefully cropped. But sometimes my artistic eye takes over and I take 'arty' shots.

I really love this image of the shadow of a fly being 'just-only touched' by the shadow of a Bramble briar. The shot is cropped only, the background being naturally under-exposed. Dunno what the fly is.

Rare hoverfly

My first trip to Mullaghagary wood for quite some time produced one of the more exciting of my hoverfly finds. The beautiful specimen below is Eriozona syrphoides (thanks to Malcolm Smart for the id). At first I thought it was a bumblebee in flight, but something said I should look closer. It landed at the bottom of a ditch - presumably to take on water in the hot weather - and I rattled off perhaps 20 shots at arms length.



This european species was first recorded in England in 1967, and was added to the Irish list in 1998, so it's clearly moving north and west. That's the end of the good news. It is only ever found near Spruce plantations (and, indeed, this was found at the edge of Spruce), so my campaign to reduce the amount of Spruce planting just took a severe blow.

Various tinies

The hedgerows are almost up to speed now that all the greenery is available. The availability of greenery brings larvae to feed on it, the presence of larvae brings ichneumonids to parasitise them. This medium-sized ichneumonid is about 15 mm. long, including those wonderful antennae.

Some of the micromoths really are minute, but many are are at least as pretty as the macros, and some are much more beautiful. This is Glyphipterix simpliciella - the Cocksfoot Moth. The larvae live inside stems of Cocksfoot grass. The adult moths are 3-4 mm. long, and can be seen running over the leaves and stems of the host plant at this time of year. The only way to see these is to lie down in a bank of grass and wait for them to land, as when they're flying around they look rather like midges:

I mentioned leaf miners earlier and they have started to appear (indeed some are finished already). This is the mine of Phytomyza chaerophylli - an agromyzid fly. One of the main identification characteristics for the mines of flies is that many of them contain a double row of frass (polite word for dung) in the mine. In these flies, the teeth are oriented in a such a way that the fly must eat right to left and then turn onto its other side and eat left to right. As it turns, its rear end points in opposite directions, resulting in the two rows of frass. The section of leaf shown here is about 15mm. across:


An easily identified hoverfly: Melanostoma scalare. I liken the yellow abdominal patches on these to oven gloves. (Female) fly about 12mm long.

One of my first butterfly images of the year: Green-veined White with the Click beetle Athous haemorroidalis (lower left).

Damsels

Damselflies are the smaller-size version of Dragonflies, with the abdomen being about the same size as a matchstick. The male of the Large Red Damselfly is bright red, with the female being predominantly green, but with varying amounts of black.


Note that the rear of the female's abdomen has been bent during the hatching process. This is a problem I've seen a few times and it will probably prevent her from mating successfully unless she is able to adapt to her 'peculiarity'.



The Common Blue Damselfly is usually more flighty than the Large Red, but this one appears to have hatched only recently. Damselflies hatch out a uniform pink colour (they are described as 'teneral' in this condition) which can be seen on various parts of this specimen. The colour soon changes from pink to the adult's normal colouring.


This close-up shows:

• The remainder of the teneral colouration, and
• The spines on the fore-legs which help to grip onto prey that is usually caught in mid-flight.

More moths

As the warm nights continue, more moths are coming to light:

First, Common Carpet - Epirrhoe alternata alternata. Food plants are the bedstraw family: probably Cleavers in my case.

Then Pebble Prominent - Notodonta ziczac. Foodplant Willow. The side-view colouration is a wonderful camouflage if seen against wood and leaves, looking rather like a cut-off branch.

Also to light, the Dark Barred Twin Spot Carpet - Xanthorhoe ferrugata.


And this pale specimen that wouldn't open its wings when landed. This specimen has mystified the good and the great: work ongoing.

Last, but certainly not least, the Small Magpie - Eurrhypara hortulata. This is one of the so-called Micromoths, but is larger than many 'macromoths'. The separation into micro and macro is an accident of history, with all species in a certain book defining the 'macromoth' list and all others being micromoths, but some larger species were simply omitted from the first book.


All species on this page are new to me.

Mimicry and more

Here's a close-up of the Bumblebee Bombus cryptarum:


Bombus lucorum was recently split into 3 species: Bombus lucorum, Bombus cryptarum and Bombus magnus. Bombus cryptarum was added to the Irish list in 2006, and consistent sampling has shown that my local population contains this species. I recently posted about the Cuckoo Bumblebee Bombus bohemicus, which was known to be parasitic on B. lucorum sensu lato, but I don't know if it also parasitises B. cryptarum or if I also have B. lucorum s-s, which I rather suspect. Work to be done, here.

The best diagnostic feature of B. cryptarum is the black notch in the forward yellow band, just in front of the wing joint:

Just as the parasite B. bohemicus is a lucorum lookalike, we also have the hoverfly Eristalis intricarius:



Note the distinctive Eristalis loop in the wing vein.

There are two main reasons for the mimicry. In the case of parasitic species like the Cuckoo Bumblebee, it may need to be able to get into the nest undetected, so it looks rather like the host. In the case of the hoverfly, it can either be to get into the nest undetected, or to fool predators into thinking that it is a Bumblebee, and can sting. Eristalis intricarius larvae live in the bottom of ditches, so they are applying the mimicry to avoid being eaten by birds.

Eristalis intricarius is known to be widespread, but in low numbers, and of the 50 or so specimens I have found over the past four years, they can all be pinned down to two separate patches of ditch, each no more than 10 metres long. So there is something that controls their distribution very tightly. To make things even more confusing, the two ditches (roughly 1.5 km apart) could hardly be less similar:

One runs North-South, the other East-West. One is at the edge of cattle pasture; the other, the fringe of a bog. One is fringed by Meadowsweet, the other Soft Rush. Just about the only thing in common is some Hawthorn and some Gorse and Bramble. Interesting......

Moths to light

On warmer nights, we tend to find more moths (and flies, etc.) attracted to light. These two species are both new to me.

Firstly, Least Black Arches - Nola confusalis - a tiny moth no more than 1cm. long:


And Yellow-barred Brindle - Acasis viretata. The fresh green colour fades very quickly to yellow.


These species are both associated with broadleaf trees and hedgerows.

Sun!

The hottest place in Ireland, today, and it showed: hoverflies and bees of all kinds were on every flowerhead.

This is another of the mining bees from my garden: the beautiful Andrena cineraria.


That shot required knowledge of the behaviour of the bee: they land and very quickly bury their heads in the florets, so all you get is an abdomen shot. But they tend to do a slow 360 degree turn before they fly off. So if you watch where they land and wait for them to complete their rotation you can get the shot as they prepare to take off.

A few butterflies are now making an appearance. So far I've seen Green-veined White, Peacock, Orange Tip and Large White. This Small Tortoiseshell is clearly showing signs of age..they overwinter as adults and have been flying around for a couple of months, now:

The hoverfly Rhingia campestris rears its young on cow dung, but it has lately been seen in urban areas, so perhaps it has migrated to domestic dung.


One of our smallest hoverflies, Syritta pipiens. The inflated thighs appear to be mimicking a minute bee which is now extinct.



And this one's for Aynia....7-spot Ladybird.

Mining Bees

Mining bees are a subset of 'Solitary bees'. Solitary bees don't form communal hives or nests, rather they make their own nest - in this case a small tunnel in an earth bank - and lay their own eggs which they look after on their own. 'Solitary' is sometimes a misnomer, perhaps, since they often form communities of individual hives clustered together in close proximity.

This is Osmia rufa on a Dandelion:



And this is the same species near its nest:


Again, notice the absence of pollen baskets: solitary bees often gather pollen by squeezing it together under the abdomen and/or thorax.

I have a south-facing bank in my garden and there are many Osmia rufa and Andrena cineraria mines all in close proximity. These bees use landmarks such as stones and sticks to find their nests and it's interesting to see how lost they become when you're sitting watching their tunnels: a human makes a serious alteration to the visual geometry of the place.