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16 July - Another sunny start. It felt quite pleasant to start with, but the temperature was over 20C before 9am and had passed 29C by 1pm.
The first Green Bush Cricket I've come across this year -a nymph about 1cm long.
Back on 21 June I came across a nursery web spider (Pisaura mirabilis) for the first time this year and commented that I have yet to see the nursery web itself in the garden.
Well, it looks as though that moment has come, in a scruffy clump that includes horsetails that I had intended to remove. That job will now have to wait a while. Sadly it seems that the spider herself has been through the wars as she has only four legs.
Her situation can be seen more clearly in this photograph. Despite what would appear to be a major handicap she is able to move around surprisingly freely. It looks as though I've been a little late in discovering the nursery as inside it you can see a single, small spider.
And looking from the opposite side it's clear that the whole brood has hatched out, quite recently too, judging by their small size. These are heavily cropped and enlarged images taken through the surrounding vegetation as it wasn't possible to approach the nursery without the danger of disturbing its silk structure.
I have to mention the caterpillars again. Having spent the night on the leaf that they settled on yesterday evening, they devoured it during the morning (its remains are at the bottom of this picture) before moving on. However, this time the group ended up split between two leaves, this photograph being taken just after 1pm,
and by 3pm they were feeding once more, with the small group disorganized, the occasional deserter moving across to rejoin the majority! By 4pm they were all together again on the lower of the two leaves. However, by 6pm they had stopped feeding with perhaps a fifth of that leaf left intact, and by 7pm the army had moved on to a completely different leaf and appeared to be resting - are they due for another moult yet?
17 July - The temperature made it to 30C again today (30.4C recorded in the shade of the birch tree, and by the end of the afternoon the skies looked threatening as Cumulus clouds built up. However, by 8.45pm I've not seen any rain, and not even heard any distant thunder. It has felt very humid today and doing much of anything has been a bit of a challenge, apart from collecting our incredibly happy grandson this afternoon to stay with us until at least Friday. During the morning I tried in vain to take a photograph of a Gatekeeper butterfly that spent a couple of hours in the garden flitting amongst the vegetation that surrounds the big pond. Unfortunately, while it landed numerous times, nearly every time it disappeared into the undergrowth. The one time that I had a clear view of it from a 'safe' distance, its reaction as I pressed the shutter was so fast that all I ended up with was a blur!
Something not interesting in moving quickly today has been the caterpillar army. They have remained on the leaf that they occupied yesterday evening and have shown no interest in eating it all day, and by lunchtime they were in the heads up posture that I last saw prior to their first mass moult. At 9pm, apart from a few adjustments in position by individuals the group's status remains unchanged.
Just a mention of the Grey Dagger caterpillar, also on the Birch. It is now at least 40mm long but I have yet to see it feeding, or see evidence of where it has been feeding. Each time I look it is on a branch rather than a leaf.
18 July - A bit cooler today with a pleasant breeze for much of the day and the temperature peaking at 28C. It was a mistake to say that I was going to cut back on my reports on the caterpillar army.
As I suspected yesterday evening, the caterpillars were preparing for moulting, and it was underway by 11pm, as a couple of bulging, orange heads indicates in this photograph.
By this morning the moult was complete (picture taken around 9am) and the caterpillars were not at their third instar stage,
This image, taken at noon suggests that the process of hardening of the skin (cuticle) was still not complete. While the leaf edges had been nibbled at, most of the caterpillars were just 'hanging about'.
There was no sign of the caterpillars on any of the leaves in the area around where they had moulted. The army was on the move up, heading up the branch, passing numerous leaves on which they could have fed.
At 7.35pm they reached a fork in the branch and headed up and out towards the canopy once more.
However, at 7.55pm the procession came to a disorganised 'dead end' as they reached what actually was the dead end of this branch.
After a short time they sorted themselves out and by 8.20pm they had settled on the first leaf that the arrived at as they retreated from the end of the branch. They are still on this leaf at 10.30pm and so far have not started eating.
Their eggs were laid 1.8m above the ground, last night's moult took place 1.9m up and tonight they are 3m above ground. I still haven't got closer to identifying the species, but today's behaviour had me taking a look at the Oak and the Pine Processionary moths, although the appearance of the caterpillars doesn't match either species, at least at this stage in their development. What other species have similar habits?
19 July - Another hot day, 27C at 3pm and reaching 28C for a short time soon after, but much more comfortable, thanks to a strong north-easterly breeze blowing through the house (which is oriented east-west). We haven't needed to resort to tower fans to encourage air flow for the first time this week. The caterpillar army is, I believe, no longer a puzzle. After I was finally able to taken some time to look I'm now sure that they are the caterpillars of the Buff-tip moth (Phalera bucephala). My Collins Field Guide to Caterpillars of Britain & Europe describes the caterpillars as gregarious for most of their life. It also describes how they will strip an entire branch of its foliage before moving on - That may apply to the caterpillars in later instar stages, but 'my' 3rd instar army seems much more haphazard in its choice of leaves to feed on.
This leaf provided their next meal of the day and by this evening they had moved on again, to the next leaf along towards the apex of the branch.
On this leaf the army has divided into two groups once again, with the majority (29 caterpillars) on the underside and the remainder (13 caterpillars) on the upper surface. At 9.15pm those caterpillars on the lower surface are feeding along the edges of the leaf, working back from its apex. In the meantime the other group seems to be resting in the middle of the upper surface.
For the first time I can see a yellow Y marking on their faces,
and each caterpillar is now around 12mm in length.
There is an indication in several sources that later instar caterpillars become solitary. Whether or not any of this brood have gone their own way I cannot be certain. For example, I don't know the fate of this individual, photographed a few leaves away from the rest this evening. It had disappeared when I checked on it a bit later on.
Whatever happened to that caterpillar, the two photographs above of the group show a total of 42 caterpillars, which is down from the 57 that I counted on the 10th, three days after hatching - 59 eggs had hatched on 7 July. With 17 out of 59 caterpillars possibly lost over a period of 12 days, and at least two more moults to go before each caterpillar has to make its way down to the ground to pupate in September, it would be very unlikely that more than a few will go on to over-winter as a chrysalis before emerging as an adult next June.
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