15 September 2009

Dragonflies and damselflies

On Saturday we visited some ponds where Fred had not collected samples before. There were large numbers of insects visiting the ponds, including these damselflies.

Male Emerald Damselfly (Lestes sponsa)

Female Emerald Damselfly

Pair of Emerald Damselflies

Pair of Darters (probably Black Darters - Sympetrum danae)

Watch a video of two pairs of Darters laying eggs.

I also found this empty larva case (exuvia) of a Common Hawker (Aeshna juncea) - one of the larger dragonflies.

One of the dragonflies even settled on Fred's head!

Many thanks to Jeanne Robinson for help with identifications.

Further information:

British Dragonfly Society - includes photos of British species
and a useful pdf document on Dragonflies in your garden

12 September 2009


On Thursday I went up Ben Venue. Close to the summit (which can be seen in this picture) there is a small pond which sometimes dries out.

Below is a photo of the pond taken early in the year, looking the other way, towards the trig point which is at the second top of the hill.

In this small pond I noticed some greenish masses and I thought this would be something to interest Fred so I tried to collect some. This proved difficult, as it kept slipping out of the collecting tube, so I used a bag instead.

Under the microscope, this turned out to be tiny protozoa, each containing green algae. We identified them as Ophrydium, though this usually grows in a much more defined greenish spherical jelly-like lumps. Maybe this was an old colony.

The creatures have tiny beating hairs at the front...

...and a long point at the rear.

Our videos:

See also:

Size dependence of composition, photosynthesis and growth in the colony forming freshwater ciliate, Ophrydium versatile. Freshwater Biol. 31: 121-130

Some notes on an uncommon colonial peritrichous protozoon, Ophrydium versatile (O.F.M.). E.D. Hollowday. Microscopy 32, July-December 1975

Hawthorn Shield Bug

Yesterday I met a small creature resembling an alien in our garden.

It was a Hawthorn Shield Bug (Acanthosoma haemorrhoidale).

It was very co-operative about having its photo taken, and afterwards I put it on a cotoneaster bush, as I think it must have dropped out of it while I was pruning.

When I went out again an hour or two later, there was a second Shield Bug sitting close by, which I hadn't noticed before. It must have been attracted by the presence of the first one.

These bugs go through five larval stages called instars.

This morning, when I went to the garden waste bin to add some more prunings, I discovered what I now recognised as an immature Shield Bug inside the bin. (I also made a mental note always to shake any prunings before putting them in the bin in future, so that these small creatures don't get sent away with the waste)

Later I found 2 more smaller ones. This is the biggest and the smallest at 11:50am...

...and the middle-sized one at 1:50pm, with the small one hiding under a leaf on the left.

1:50pm. The biggest and smallest. The smallest had already changed colour, so it must have gone through a moult.

17:30. I went to have another look, and the biggest one had now changed completely. I think this is the 5th instar stage.

17:45pm. Meanwhile, the smallest seemed to be moulting again.

8th October 2009

Today I found this shieldbug crawling on the lid of one of our compost bins. It is a Birch Shield Bug (Elasmostethus interstinctus) and it measured 8.5mm excluding the antennae - slightly smaller than the Hawthorn Shield Bug. Note that the projections on the pronotum (the widest bit just behind the head) are smaller and not tinged red.

16th October 2009

It has been a while since I saw any Hawthorn Shield Bugs, but I discovered this 5th instar today on the cotoneaster bushes.

More information can be found on the British Bugs website.

11 September 2009

Emperor moth and caterpillar

Yesterday I was out for a walk up Ben Venue in Perthshire.

While we were walking through a rather boggy area, I met this HUGE caterpillar. It was probably about 6cm long, though I didn't measure it.

Usually, attractive caterpillars seem to end up as rather dull moths, but not this one. It is the caterpillar of the Emperor Moth (Pavonia pavonia). I had found one of these moths on the hills on 14th April 2007, and it is truly spectacular. The larger female, shown here, is not often seen because it mostly flies by night.

05 September 2009

Bog orchids

The Bog Orchid - Hammarbya paludosa - is a rather rare orchid which grows in scattered locations throughout the UK, particularly in the west of Scotland. It flowers from late July to September.

I was keen to see this tiny orchid, and jumped at the opportunity when, on 1st September 2002, I was invited to go and look for it at a location where it had been found before. Unfortunately the arranged trip fell through, but I decided to go and have a hunt for myself in a different area, preferring somewhere less remote when walking alone.

I hadn't been walking for long before I came to a likely looking boggy area. You can imagine my astonishment when I found 14 Bog Orchids scattered along the side of a small stream! This was within a site which was already designated as an SSSI, but Bog Orchids had never been found there before. This site in Stirlingshire has continued to be a reliable location, and this year we found 51 flowering spikes there.

Bog Orchid at the site found in 2002, 8th August 2009

This was certainly a case of beginner's luck. Although we later found them at the site which we had intended to visit on that first day, I did not see them at any other location until this year despite looking out for them in any bogs I happened to be passing.

On 22nd August this year I went hill walking with a group. The pace was rather fast for flower hunting, but I can't walk anywhere at this time of year without keeping a look-out for anything unusual. We hadn't walked far before I noticed 2 Bog Orchids beside a wet flush, and 4 more close by. I could not stop to look for more, but on the way down I made sure that I was ahead of the rest and found a total of 9 flowers. This site in Perthshire was also an unknown location for the orchid.

To give some idea if the small size of this orchid, the length from the bottom of the lowest floret to the top of the spike in this picture measured 13mm. In the Bog Orchid the flowers twist through 360 degrees rather than the 180 degrees of most other orchid florets - so the florets appear upside-down compared to other orchids. The green-striped lip can be seen at the top of the upper floret on the right.

Since I discovered this site, I was asked to check on a site in Perthshire where this orchid had been found in 1999 but the grid reference was thought not to be accurate and it had not been seen since. This was a real challenge, as the Bog Orchid particularly likes growing on moss or peat where it is alongside a stream or water with some movement, and it turned out that the whole area was suitable habitat with many wet areas, small streams and bogs. Fred came with me, and we searched all the likely areas, working in a zigzag from the first stream we came to until we reached the given grid reference. We had searched for more than an hour and were about to give up when I suddenly found one.

The site was typical - a wet flush with water trickling down it into a nearby stream.

My stick marks the location of this plant.

Perhaps because it was towards the end of the season, it had quite a yellowish colour which made it slightly easier to spot, and a further search produced 7 more flowers.

The picture below shows this plant in its habitat, with a Round-leaved Sundew growing nearby on the left.

01 September 2009


The tube-building sessile rotifer, Floscularia ringens

A rotifer is a microscopic animal that is mainly found in fresh water. There are about 600 species found in the British Isles.

Tube-building rotifers are difficult to observe, as they withdraw into their tube with the slightest vibrations. This makes it difficult to take still photos, and more so to take a video clip.

This shows the rotifer causing currents in the water as it draws food into its mouth.

When the eggs of this rotifer hatch, they are free-swimming until they find the leaf of a water plant. Each species of rotifer uses a different type of plant. Some species will only attach themselves to the upper or lower surface of the leaf. The animal builds its protecting tube from debris it collects and the waste from its digestive system. The pattern of the pellets the tube is made from is specific to each species of sessile rotifer. Once the rotifer attaches itself to its chosen leaf, it never moves from this position.

There is more information about rotifers on our site.