Sunday, 27 September 2009

A miscellany

Every tree has its set of dependent species. Horse Chestnut has fewer than most, but I strongly suspect that the number of dependent species is closely related to the length of time that a particular species of tree has been resident in a particular place: it will always take some time for the dependents to follow the presence of the host. Horse Chestnut is a relatively recent addition to our fauna, and would almost certainly have been introduced by man. I must see if it's possible to detect a statistical correlation between duration of residence of host plant and number of dependent species.

The fungal rust on this Chestnut leaf is Guignardia aesculi, which affects most specimens of Chestnut in our area.

Moths are still coming to light, but in smaller numbers, which is to be expected as we get colder. This Black Rustic - Aporophyla nigra - is a new species for me:

Occasionally I get an Ichneumonid or two as well. This red one is worth showing:

Shield bugs are usually found very close to their particular habitat. This Forest Shield Bug - Pentatoma rufipes - is always found in old deciduous woodland, but the other night this specimen was blown onto my windowsill. It can always fly back.

Monday, 21 September 2009

Late Campodorus shots

Since the sawfly larvae are now nearly full size, and the leaves are turning brown, I don't think I'll get too many more shots of the Campodorus.

The first shot shows the Campodorus ovipositing into a pavidus larva that is just on the other side of the leaf, through the hole. I have no idea how she knows where it is. Note the wings held high, presumably to protect them from damage should the sawfly flail around, which they often do.

In this next instance I watched the whole approach. The Campodorus walked from a higher leaf and arrived on the leaf shown. Within a second she had spun round and tried to lay in the tail of the larva, but its reflex triggered and she was thrown about a centimetre away. Undaunted, she tried a very slow, sneaky, second approach, this time aiming for the front of the larva, which doesn't move during the reflex. The reflex was triggered a second time, but she was untouched and continued to lay.

Sunday, 20 September 2009

Sawflies again

The first batches of Nematus pavidus larvae are almost full size now, so I suppose they'll soon be moving down the branches to overwinter.

The Campodorus females are still lurking, laying eggs when they get a chance, although I haven't seen any of the Mesochorus females for about a week, now. This shot shows full-size larvae with a Campodorus female in the centre of the leaf:

Notice a family resemblance? This is another sawfly larva that I find from time to time on either Bramble or Raspberry. No id, yet.

Tuesday, 15 September 2009

Drumboe fungi

Drumboe is that rarest of urban ancient woodland. Native trees 200 years old rub shoulders with introduced species of all kinds on the banks of the river Finn a mere 100 metres away from a bustling town centre. It's a little more 'managed' than I'd like, but it's still a wonderful place to visit for fungi at this time of year.

This young Fly Agaric - Amanita muscaria - has only just surfaced, and already it has been nibbled:

The remains of a Stinkhorn - Phallus impudicus - after the dark brown spore mass has been removed by flies:

An Earthball - Scleroderma citrinum:

Mycena pura, which smells 'raphanoid' - strongly of raw potatoes or radishes:

A single specimen of Chanterelle - Cantharellus cibarius - was confirmed immediately by the appearance of the thick, forked, gills:

Sadly, a single specimen isn't enough to eat, but the perfume now lingers in my study.

At first I thought these might be Jelly Baby - Leotia lubrica - but the stipe is wide and creamy-opaque (see top specimen). So they will go down as Cortinarius sp.

A batch of Honey Fungus - Armillaria mellea - suggests buried dead wood at this spot.

Sunday, 13 September 2009

Full Sun

At last, a shot of the primary parasite at work:

Every batch of larvae had an attendant female wasp.

The summer weather has been so bad that this is the first dragonfly I have seen this year. Red Darter, female:

And last night to light, along with several Dark Marbled Carpets and Frosted Orange moths, this Nicrophorus investigator beetle with its obligatory mites (notice the two behind the eyes).

New to me.

Friday, 11 September 2009

New moth

While I was watching the Campodorus (the primary parasite) continuing to parasitise the sawfly larvae, I noticed this bright green caterpillar on an upturned leaf on the same willow. The spiky 'tail' suggested a hawkmoth of some kind, but I wasn't sure which one. A fairly quick search on the excellent turned up a version of the Poplar Hawkmoth. This was a bit of a surprise, but a little research shows that it's often found on willow, too.

New to me, although it's common enough.

Thursday, 10 September 2009

Campodorus/Mesochorus timings confirmed

The secondary parasite - Mesochorus sp. was seen ovipositing late on September 9th. First as an atmospheric sillhouette:

And then in full glorious colour:

Notice that the larvae are not exhibiting their normal defensive reflex. I think this is how the Mesochorus females detect the presence of the egg of the Campodorus.

So we have a timing of 2 days from primary parasitisation to secondary parasitisation. It is clear that the secondary parasite is targetting the egg of the primary parasite. This actually makes more sense. (See the full discussion on

As an aside, the primary parasite was still lurking: there are other batches waiting for her attention:

Wednesday, 9 September 2009

Lichens - fungi that have learned the art of gardening

Lichens are a familiar sight on walls and trees, especially in areas free of pollution. They are the pioneers of the natural world, living in often hostile conditions, and converting stone and wood into soil. The following image is a wonderful example of this pioneering process:

The fencepost which forms the basis of the eco-system we see in the image was put in position around 50 years ago. A series of lichens would have appeared very quickly in succession, each one preparing the post for the next. As the lichens died they would leave dead fungal matter, dead algae and rotted wood. Sooner or later a moss spore will have found this mixture suitable as a substrate and the moss began to live (and die) there. This decomposed vegetation eventually provided sufficient soil for the Bilberry to take root. So in a very short number of years, we have a sterile fencepost being turned into a habitat suitable for fruiting plants. It should be noted that the post still hosts a number of lichens and mosses in addition to the Bilberry. The process on stone takes slightly longer.

If you read any literature on lichens, you will be told in no uncertain terms that "lichens are a symbiotic relationship between a fungus and one or more algae or cyanobacterium". Whilst it's true that each lichen contains a fungus and one or more algae, with the combination being named after the fungal partner, I think the relationship is rather one-sided:
  • Firstly, the algal partner can - and often does - survive on its own, whereas the fungus cannot. (Typical examples are Trebouxia and Nostoc, both of which I have found growing freely in a number of places.)
  • Secondly, the reproductive system of a lichen is either purely fungal, or a combination of a fungal component with a captive parcel of algae.
We need to look at what each partner adds to the relationship. Clearly, the alga produces energy from sunlight - something the fungus cannot do, so the fungus is the major beneficiary here. The fungus provides the physical structure of the lichen - basically a house for the alga, which is constrained by the lichen, and is only able to reproduce within the confines of that structure, and is unable to free any part of itself as independent offspring. It seems to me that the alga is trapped and imprisoned by the fungus largely for the benefit of the fungus. Hardly a fully symbiotic relationship.

The following image shows the fruitbodies of a lichen that clearly demonstrates the fungal nature of the reproductive system. Lichenomphalia umbelliferae is a lichen that grows in association with mosses. The fruitbodies are about 10 mm across the cap.

The actual situation is much more complex, of course, with some fungi that can be part-time or opportunistic lichens. A couple of years ago, I took this picture of Boletus erythropus with a golfball-sized lump of algae on its stipe. Notice the lichen-like appearance of the surface of the lump.
This 'skill' of harnessing the photosynthetic properties of algae must be deeply embedded in fungi.

Tuesday, 8 September 2009

Hateful weather

The Nematus pavidus larvae continue to grow and are currently on their third leaf. The oldest specimens have shed twice and are now in their third instar. The colour pattern is more or less set now and larvae are about 10mm long:

Primary parasitisation by the Campodorus was observed yesterday, but I didn't manage to get a photograph.

The second batch, based on the eggs I showed on 27th August is still on the first leaf, and has been reduced to 21 from the original (very small) batch of 29 eggs and hatchlings.

I suspect this was a final, almost throw-away, batch (most 'normal' batches contain 50-100 eggs), and the benefit of safety in very large numbers will not apply to this batch.

I spotted a pair of Picromerus bidens in cop on Bramble:

A local chap proudly brought me a pair of Giant Puffballs that he'd spotted on a nearby verge. Sadly, he didn't want to leave one with me for dinner:

Specimens about 30 cm. across.

Just for the record, we have had rain every day since 15th June.

Wednesday, 2 September 2009

Nematus update

The first willow leaf has now almost been consumed, so the trek to the next leaf will commence very soon. Notice how all of the larvae have migrated to the stalk end of the leaf in preparation for the journey. Larvae are currently about 4-6 mm long.

And here's the bad news as far as the larvae are concerned. This is the primary parasite, a Campodorus sp. Ichneumonid. This is the one that oviposits from under the leaf, curling its long abdomen round the leaf edge. The larvae are currently too small to target, but I suspect egg-laying will commence in a day or two.

Interestingly enough, this specimen was checking out individual leaves and then walking along the willow twig to the next leaf. I suppose it's making sure the trekkers don't escape its attention.

A very common leaf-miner found on Alder is the Sawfly Fenusa dohrnii. This makes a brown blotch mine that wanders between two veins, heading towards the leaf edge.

This close-up of the larva shows the distinctive shape, with wide 'shoulders', which confirms that we are looking at a sawfly rather than a fly, which has simple bullet-shaped larvae.