7 posts tagged with

caterpillars

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Old photos, new IDs: setting the record straight

When I posted this photo back in September 2009 (‘A late summer’s wander’) I was unsure what species of fungus I’d snapped. Chicken o’ the woods (Laetiporus sulphureus) was what I was leaning towards, but I wasn’t 100%. Yesterday I chanced upon a familiar-looking specimen in my mate’s guidebook, Mushrooms and Toadstools of Britain & Europe (a Collins Nature Guide). I can now exclusively reveal that the fungus in my photo is a… dyer’s mazegill - Phaeolus schweinitzii (deprecated synonym: Phaeolus spadiceus) - a polypore fungus that forms fruiting bodies on the roots or bases of conifers such as pines, spruces, firs and larches. My specimen was growing at the base of a Scots pine (Pinus sylvestris) in Millstones Wood.

I first posted this photo of a ‘caterpillar’ eating one of the treeblog Set A grey alders (Alnus incana) in October 2009 (‘Two species of caterpillar on the grey alders’). I had no idea what species it was but I believed it to be a caterpillar – i.e. the larval form of a moth or butterfly. I discovered a few weeks ago, again by chance, that this attractive creepy-crawly is actually the larval form of the hazel sawfly a.k.a. birch sawfly (Croesus septentrionalis). The larvae feed on hazel, birch and alder leaves and strike this curvaceous pose when disturbed. Interesting fact: true caterpillars have five pairs of prolegs or less, but hazel sawfly larvae have more than five pairs (see this forum page).


Posted in Miscellany





Two species of caterpillar on the grey alders

Earlier this afternoon I noticed several caterpillars on two of the Set A grey alders (Alnus incana). There were a few colourful caterpillars munching away on grey alder No. 3 and there were several white “snowflakey” caterpillars on grey alder No. 2. These snowflake caterpillars have been on the alders since at least mid-August and they seem to have some kind of magic power that can prevent a camera from focussing on them. They eat in random patches to leave the leaves full of holes like a Swiss cheese whereas the colourful, curly caterpillars eat in a more systematic fashion, devouring neat sections between veins. These caterpillars stand with their tails sticking up into the air; when I got close to them they gave them a little wave.

Last year there were two or three other species of caterpillar on the alders. Have a look at all the posts tagged with ‘caterpillars’ if you’re interested!

By the way, I’ve no idea what species either of these caterpillars belong to. Leave a comment or drop me an email if you know what they are, please!

Update (July 2010): The black and yellow ‘caterpillars’ are actually larval forms of the hazel or birch sawfly (Croesus septentrionalis).


Posted in Pests and diseases + The treeblog trees





treeblog update (Set A, Day 875): Scots pines (& grey alders). Eggs & caterpillars. Eucalyptus flowers.

Scots pine Alpha earlier today (Day 875).

Scots pine Gamma.

A bit of an eclectic post is this one, gang! First of all there’s a bit of a treeblog Set A update, but only for the two Scots pines (Pinus sylvestris), the post-Set A goat willow (Salix caprea - formerly the PSAUS), and one of the grey alders (Alnus incana). Normally I’d lump the pines, willow and all the alders together but I haven’t been able to this time because the grey alders are too big. I like to have a nice, clear background on these update photos y’see, and for most of the Set A trees I have a piece of plywood that’s perfect for the job. This summer the grey alders have outgrown it by quite a ways. I had a background trick up my sleeve for the last Scots pine & grey alder update (27th June – Day 822) though: I hung a grey blanket from the washing line. But in the intervening one-and-a-half months (sorry for the wait) the alders have rocketed up and are now so big that even my double-bed sheet hung from the line is too small to make do! What I tried for a background this time around – a wall of conifer – has proved so useless I’ve only bothered putting up one of the photos. A green alder against green conifer scales. It doesn’t exactly stand out from the background…

Grey alder No. 1 (with decreased brightness and increased contrast). Well camouflaged, eh?

Ohhh, by the way, I got out the tape measure and took some heights. I did the same when I did the last update, so now we know how much the trees grown in the last 53 days:

Scots pine Alpha: 27 Jun: 48 cm  //  19 Aug: 50 cm  //  Difference: 2 cm.
Scots pine Gamma: 27 Jun: 27 cm  //  19 Aug: 30 cm  //  Difference: 3 cm.
Grey alder No. 1: 27 Jun: 105 cm  //  19 Aug: 196 cm  //  Difference: 91 cm.
Grey alder No. 2: 27 Jun: 71 cm  //  19 Aug: 150 cm  //  Difference: 79 cm.
Grey alder No. 3: 27 Jun: 109 cm  //  19 Aug: 170 cm  //  Difference: 61 cm.
Grey alder No. 4: 27 Jun: 120 cm  //  19 Aug: 186 cm  //  Difference: 66 cm.
Post-Set A goat willow: 27 Jun: 25 cm  //  19 Aug: 33 cm  //  Difference: 8 cm.

That’s right! Grey alder No. 4 has lost its status as treeblog Champion to grey alder No. 1!!! Sensational!!! Grey alder No. 4 (the Beast) has been the tallest treeblog tree since early June 2007, when it took the crown from Scots pine Alpha. Other changes in the last month and half include grey alder No. 1 nearly doubling in height and grey alder No. 2 more than doubling in height! Some of my trees, that I planted two-and-a-half years ago, are now taller than me!

The post-Set A goat willow. See that bit of yellow on the uppermost leaf on the right-hand branch of the fork?

It looks like some kind of nasty fungus that is killing the leaf and the terminal leaf bud. I think the same thing may have happened last autumn which caused the seedling to fork. Will this branch end up forking again? Why is this happening? Is it something young willows are prone to?

Back to grey alder No. 1. On the underside of one of its leaves, this strange caterpillar that looks a bit like it’s covered in tiny flakes of coconut (like those you get on Tunnock’s Snowballs). No matter how hard I tried, I couldn’t get the bugger in focus, but I think it’s clear enough for someone out there to make an ID. Anyone?

That was today. I photographed this patch of eggs on one of the alders’ leaves on the 9th of August just as tiny-weeny caterpillars were hatching out.

These insect eggs were spotted on Scots pine Alpha the same day. I don’t know what was in them, but they have all hatched and a new batch has been laid since.

Cider gum No. 14’s flower buds still haven’t opened. Here they are on the 9th, and they look pretty much the same today.

When I was up in the Highlands for the first week of August, the cottage we stayed in had a young eucalyptus (about ten to fifteen foot tall) growing in the garden. This is one of its flowers. I don’t know what kind of eucalyptus it was, but it’s quite possible it was a cider gum (Eucalyptus gunnii) like mine.


Posted in The treeblog trees





treeblog's cleft-headed looper (Biston betularia) - larva of the peppered moth

A couple of posts back, in the most recent grey alders and Scots pines update, I published a couple of photos of a rather spiffing caterpillar pretending to be a twig on treeblog’s grey alder No. 1. That was on Friday the 7th of November. A week later on Friday the 14th, when I was taking photographs for the cider gums update, I saw that Bud-head (for so I called the caterpillar, after its spectacular bud-mimicking head) was still on alder No. 1. What a beaut! But when I went to check on old Bud-head a couple of days later on Sunday, it was gone. Vanished! Nowhere to be found!

Bud-head on Friday the 14th of November.

What species was Bud-head? I wondered. What would it look like as a moth or butterfly? I didn’t hold much hope that I’d ever find out, after failing to identify the other caterpillars that called the grey alders home this year – see these posts from October and August. But after opening my Insects of Britain and Northern Europe Collins Field Guide, I found what I was looking for pronto. Bud-head is a Biston betularia (L.) – a peppered moth (or, when in caterpillar form, a cleft-headed looper). I was pretty impressed. Peppered moths provide one of the best-known examples of survival of the fittest – probably the most taught example in British education establishments! For those who aren’t in the know…

There are two forms or morphs of peppered moth; one light-coloured and the other dark-coloured, or melanic. Before the Industrial Revolution, most of the peppered moth population was made up of the light-coloured form. Yet once the Revolution kicked off, the dark-coloured form rose to dominance. The accepted theory puts this change down to air pollution. All of the soot and smoke kicked out by the dirty industries of Britain coated buildings and trees. The light-coloured moths used to have a good set of camouflage, but on the blackened, sooty surfaces of the Industrial Revolution they stood out like sore thumbs. At the same time the melanic form fitted in nicely; they suddenly had the superior camouflage. So while their lighter brothers were sitting ducks for predators, the dark-coloured moths thrived. Nowadays, after the decline of our heavy industries, there is less soot and smog in the air, so guess what? The lighter-coloured form is making a comeback.

I’ve just whacked all that down from memory, but if you do some digging, I’ll bet there are some good papers out there with the science to back it all up. Incidentally, judging by its colouring Bud-head is probably of the melanic form (f. carbonaria). Another interesting fact (lifted from the Collins Field Guide):

The name of the family [Geometridae] means ‘ground-measurer’ and is derived from the behaviour of the caterpillars. These are generally long and slender and they have only two pairs of prolegs… When walking they grip the substrate with the prolegs and then stretch out, as if measuring length, to find a hold with the thoracic legs. Having found a hold, they draw the prolegs up close to the thoracic ones and in doing so they throw the body up in a loop – leading to their common name of the loopers.

The Collins also adds to my light-dark story. Apparently the melanic form was first reported in 1848 (the Industrial Revolution took place around the late 18th and early 19th centuries). And:

It is believed that the larvae of the melanic form are hardier than those of the normal moths in the presence of slight air pollution – insufficient to blacken trees and walls. Industrial melanism occurs in many other moths, and in some other groups of insects as well, but in recent years there has been a noticeable drop in the numbers of melanic individuals as a result of smokeless zones in many regions.

Bud-head from behind - now probably gone off to pupate in the soil for overwintering.

Read about the peppered moth on Wikipedia.

Update (26th November 2008): I've had it brought to my attention that this post would be improved by including a picture of the peppered moth. I'll go one better and include two.

Probably the intermediate form, Biston betularia f. insularia. © naturalhistoryman (Flickr).

The melanic form, Biston betularia f. carbonaria. © naturalhistoryman (Flickr).


Posted in Miscellany





treeblog update (Set A, Day 590): grey alders & Scots pines

treeblog update time for Set A’s four grey alders and two Scots pines! Photography from this afternoon, 590 days after the seeds of Set A were sown.

(From left to right) I present to thee grey alders One, Two and Three. Still bravely holding onto their caterpillar-savaged leaves despite the ravages of autumn.

Grey alder No. 4, treeblog’s greatest son.

Scots pines Gamma (left) and Alpha (right). All of the juvenile needles on both SPs have now turned yellow, although it is tricky to see in this little photo (click the picture to see a larger version on Flickr). The adult needles, which are always arranged in pairs on Scots pines, stay green as these guys aren’t deciduous. Check out SP Alpha’s two little chimney sweep brush-esque branches. I predict great things from those next year.

Bonus “treeblog’s good for insects” photos

I found this excellent caterpillar right at the top of grey alder No. 1. Isn’t its head an incredible imitation of a bud! This was the only one I could see on the alders today – no sign of the other caterpillars.

Take a closer look at that awesome bud-head. My sister reckons it looks like a meerkat looking backwards over its shoulder!

A lovely leafhopper on grey alder No. 4. I saw a few more of these guys chilling around.

The next post should be the cider gums' turn for an update, weather permitting. ‘Til then, sayonara!


Posted in The treeblog trees





Caterpillars on the alders

two caterpillars in alder leaf den

(The photos in this post can be viewed at a higher resolution – click them to open their Flickr pages, then click the 'All sizes' button.)

caterpillar hiding between alder stipules

silky caterpillar den on alder leaf

two caterpillars hiding between alder stipules

treeblog’s grey alders sure have received a pasting from caterpillars this summer, No. 4 being the worst affected. Back in mid-August I posted a photo of a cluster of small translucent and green caterpillars on alder No. 1. Much bigger caterpillars are still munching away – I’m assuming that these are more mature specimens of the flavour photographed in August and not caterpillars of a different species. The four photos above were taken nearly three weeks ago on the 28th of September (the date of the last grey alder and Scots pine update) and show the big-size caterpillars. If anybody recognizes this species please email me at the address shown at the top of the page.

P.S. Earlier today... a third v. successful nut-collecting trip to that sweet chestnut!


Posted in The treeblog trees





treeblog alders host to caterpillars and insect eggs

There is bad news for treeblog’s grey alders: they are getting nibbled on! The cider gums and the Scots pines remain unnoticed by pests but the four alders are hosting aphids, caterpillars, leafhoppers and/or froghoppers, miscellaneous eggs… and those are just the things that I’ve noticed. Many of the leaves are full or holes or are blighted by conspicuous dead patches. Some parts of leaves have been folded over and glued together by the silk of tiny caterpillars.

All of the photos in this post are of grey alder No. 1, one of the worst affected by these insect terrors.

swarm of tiny caterpillars on alder leaf

Tiny caterpillars swarm on the underside of a badly damaged leaf. [7th August]

damaged alder leaves

A view of the upper side of the same leaf alongside another leaf, damaged but not yet even fully unfurled. [7th August]

insect eggs beneath alder leaf

Insect eggs on the underside of a leaf, seen on the 7th of August. Notice the two oval eggs on the left, obviously belonging to a different species than the main body of round eggs.

insect eggs beneath alder leaf

A day later, on the 8th, and the round eggs have changed from white to caramel in colour.

insect eggs beneath alder leaf

A closer look reveals the eggs to be patterned, I guess from when they were squeezed out by the parent.

insect eggs beneath alder leaf

A few days later on the 12th of August and the eggs are now a dark purple / slate greyish colour. When will they hatch, and what will come out of them?

insect eggs beneath alder leaf

Update: The same cluster of eggs on the 15th of August. Notice how the two white eggs on the left have now hatched.


Posted in The treeblog trees





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