A couple of surveys

I was invited to help with a couple of surveys this week and found some interesting specimens. The first location was a disused mill with associated ponds, dams, millraces and reservoirs. This is a wonderful site covering tens of acres, with old deciduous woodland and various meadows in addition to the water features mentioned above. It was also on limestone, which I always find interesting. Sedge and grass specialists would have a field day here. We were actually hoping for butterflies, but it was dull and wet, so I concentrated on leafmines, which are always there despite the weather.

First interesting specimen was this one on Ground Elder:

Blotch mine on Ground Elder

Most mines are specific to family, perhaps even species of plant, but this is the mine of Phytomyza angelicastri, which is more usually found on Angelica. So this isn't a new mine for me, but it is a new host for that species. I can now add that insect to plant association in my Donegal Wildlife database.

There were a couple of specimens of Early Marsh Orchid in the middle of a path next to one of the ponds:

Early Marsh Orchid

Sawflies are one of the least-studied groups of insects. They are difficult to identify to species, often requiring dissection for a certain identification. The larvae are also poorly documented, and since they can change their appearance dramatically when they shed their skin, identifications are very tricky. One or two species can be identified from photographs, but first you have to eliminate similar-looking Ichneumonids. This is the sawfly Tenthredo livida (male):

The sawfly Tenthredo livida (male)

One of the main characters that can be used to separate Ichneumonids and Sawflies is the microsculpture on the thorax. In this case, it looks like the letter 'M':

Close-up showing microsculpture on the thorax

Ichneumonids tend to have a smoother thorax, although that's not a hard and fast rule.

This Eristalis hoverfly caused me a few id problems.

Eristalis nemorum  (male)

One of the main keying features for these is the facial stripe, which is more or less absent on this specimen. So that immediately keys to Eristalis arbustorum. But this didn't look right for that species. The key caters for specimens of E. arbustorum with a slight facial stripe caused by wear and tear, but this still didn't key out properly until I took into account the very narrow stigma (dark thin line) on the outside edge of the wing. This is a feature of Eristalis nemorum, which I am now told can sometimes be found with no facial stripe. I suspect that some of this variation is caused by the fact that my local specimens are found on acid soil, but this specimen was on lime.

Caddis flies are always found near water, since the larvae live at the bottom of ponds, ditches, etc.

Caddis Fly

Shield Bugs, in common with all other Heteroptera, go through a series of nymph stages before becoming adult. In each stage they become slightly more like the adult in size and pattern. This appears to be a final-instar (full-size, with larger wing-cases) nymph of Pentatoma rufipes:

Final instar nymph of the shieldbug Pentatoma rufipes

 There was a family of Mute Swans on one of the mill ponds:

Mute Swan and cygnets

I wouldn't normally go near swans with cygnets, but I was advised that this pair were calm enough. The male quickly got between me and the family and hissed a bit, but stayed to the side, watching me until he saw that I was just taking photographs. Interestingly enough, this is new to my species list.

All in all a lovely location that I will revisit in the future.

Sunny August

In this shot I tried to show the extensive Fuchsia hedging that paints much of western Ireland red at the moment, but the very bright sunshine made a decent shot very tricky.

Fuchsia hedging at Mongorrey

Note the very straight road stretching all the way westwards to the horizon. I had always thought that these long straight roads must be Roman roads, but the Romans never got this far, and the roads are known as 'Famine roads'.

The white umbellifer plants at the front of the shot are Angelica.

Many of the wasps that can be seen slowly crawling over umbellifers at the moment are males:

Male Vespula rufa

Vespula rufa can be identified by a combination of features including the red areas on the abdomen, facial markings and stripes on the thorax.

This Chloromyia formosa soldier fly was happily nectaring on the Angelica......

Chloromyia formosa soldier fly

until a Tenthredo sp. sawfly decided it would make a good meal and jumped on it:

Chloromyia formosa escaping from a Tenthredo sp. sawfly

Even at 1/120th of a second, the fly is just a blur.

It's not only the flowers of Angelica that attract insects: leaf-miners are also present. Phytomyza angelicastri is one of two species that I find locally:

Phytomyza angelicastri on Angelica

The Hawthorn parasite Taphrina crataegi clearly has some special habitat requirements. This is the only tree that I have found to be infected on my patch:

Taphrina crataegi on Hawthorn

I have also found it in one location in Northern Ireland, and in each case the tree overhangs lying water, but I know of many Hawthorns in similar situations that are unaffected, so it must be something more subtle.

As I was searching along a verge, a shadow passed over me and I looked up expecting to see a bird, but it turned out to be a huge Common Hawker dragonfly which was hunting along the same verge. I followed it for a while and it eventually rested on a Willow, so I managed to squeeze in a few distant shots:

Common Hawker dragonfly

And nearby I saw a Common Darter landing on a grass stem. She tolerated me for quite a while before flying off:

Common Darter dragonfly (female)

Slender St. John's Wort is my favourite flower, so I made an artistic crop of this pair:

Slender St. John's Wort

Fungus time again

With all the rain we've had this year, I rather suspect we're going to have a good year for fungi: I'm seeing a few on the verges and in my garden, and yesterday I found this season's first specimen of Entomophthora muscae on a hoverfly. In my previous post, I mentioned that the Taphrina fungus alters the growth of the Alder for its own benefit by creating a large surface area for spore production and dispersal. This ability to alter a host for their own benefit is a recurring theme with fungi, and I never cease to be amazed at the lengths they go to in order to achieve this aim.

Entomophthora muscae is a fungus that uses flies as a tool for its spore dispersal. The fungal spores are ingested by the fly and the fungus rapidly grows inside the fly's abdomen. Eventually, the pink fungus breaks through the structure of the abdomen and becomes visible for a couple of days before it breaks down and the spores are released.

This is the shot of the hoverfly from a top-down perspective:

Hoverfly killed by the fungus Entomophthora muscae

The pink fungus can clearly be seen emerging from the abdomen of the hoverfly (which, unusually, is a Platycheirus species: Melanostoma scalare is the most frequent host in this area).

Two aspects of this photograph are of critical importance:

1) the hoverfly is at the very top of the plant (Ribwort Plantain)
2) the wings of the hoverfly are fully extended in an unusual forward-facing configuration

Both of these features will allow maximum airflow over the fungal mass and, more importantly, both are caused by the fungus. Before the fungus kills the fly, it causes it to move to the highest available point and then open its wings to the fullest extent. Then it kills it.

This ability of the fungus to control the fly's movement and configuration for its own benefit is astonishing enough, but it works with different flies from different families, so the fungus has found a way to control the movement of a whole range of different fly species.

Another feature of the configuration control is shown in this side view:

Side view of the fungal mass

The legs have also been fully straightened: yet another part of the configuration that maximises spore dispersal: truly amazing.

The fungal mass will break down and release spores over the next couple of days, leaving just a skeletal husk of the hoverfly on the plant.

It's not only nectaring insects that benefit from the Angelica. This is a shot of the miner Phytomyza angelicastri on the leaves:

Leaf-mining fly Phytomyza angelicastri on Angelica

The Rosy Rustic moth pupates underground until August, and this pristine specimen was resting on a low-level Dock leaf, so I rather suspect it had just emerged.

Rosy Rustic moth

 

Aphids in trouble again

I noticed that the Knapweed was covered in brown aphids, so I settled down to see if any female hoverflies came along. Sure enough, a female Episyrphus balteatus arrived and as soon as she spotted the aphids she started to lay. The aphids are in trouble, since her larvae will consume them by the hundred.


Sometimes she laid her eggs quite distant from the aphids (but always on the same plant). At other times she laid a lot closer:


Spiders are the major gap in my knowledge. I must start on them next year.

I was getting acquainted with emerging specimens of Angelica, in preparation for the July flowering, and I spotted this mine of Phytomyza angelicastri:


A couple of additional images of Dactylorhiza orchids with slightly unusual markings. This one has very vague nectar guides:


And this one has nectar guides which are much redder than usual: