Leafcutter bees

I am always impressed at how obliging wildlife can be when we try to attract it to our gardens: put up a bird box and before long it will be occupied by a blue tit, dig a hole and put some water in it and as if by magic a whole wealth of aquatic creatures will appear. This year we put up a solitary bee home, and lo and behold, solitary bees appeared. It was fascinating to watch them as they went about their business, and highly impressive to see the rate at which they made the tube-filled log their own.

Most people imagine bees to be highly social creatures, living in large colonies to do the bidding of an all-powerful queen. This is indeed the case for common bumblebees and honey bees, but there also exist a number of solitary bee species, of which the leafcutter bee is one example. Leafcutters are fairly small bees at about 10 mm long. Their bodies are a dark brown with a dip in the abdomen where they store pollen; this differs from other bees which store pollen in sacks on their legs. They don't live long, normally only for two months, but they fill this brief existence with frantic activity

Upon emerging from its nest the female bee quickly finds a male with which to mate. Once it has done this it goes about finding a suitable nest site, ideally somewhere providing a hollow tunnel of a similar width to the bee itself, although it can dig out a tube if necessary. The nest could be in the stem of plants such as roses, in the soft depths of decaying wood, or in the tubes of a shop-bought bee home. Once a site has been located the bee will start collecting leaves. Whole leaves would be rather awkward for the little bee to carry, and so instead it cuts out small semi-circles which it carries back to the nest. It then uses these to fashion several compartments in the previously-constructed tunnel, into each of which it leaves an egg and a ball of pollen and nectar before sealing it up. Once the nest is completed the bee abandons it to fate.

Each female leafcutter bee lays up to 40 eggs, which means up to 40 compartments need to be made - this equates to an awful lot of leaf building material and explains why the bees are so busy. Life for the larva is rather more sedate. It soon hatches and consumes the ball of pollen left for it, then hibernates for the winter. The following spring it comes round and pupates, emerging as a fully-fledged bee at the beginning of summer. Males tend to develop in the compartments closest to the end of the nest, and so emerge first. Their sole purpose is to mate with the females, and after they have done so they die, taking no part in the nest-building process.

Millipedes

There are around 8000 different species of millipede in the world, of which 52 are present in the UK. The name 'millipede' translates as ‘thousand legs’, and although these creatures are indeed many-legged none of them quite reach the thousand mark, with 750 being the record (held by Illacme plenipes of the USA). Their bodies are made up of multiple segments, most of which carry two pairs of legs and are protected by a chitinous cuticle. The different segments are connected together by ball and socket joints, allowing the creatures to be incredibly flexible, and they will often curl up into a compact spiral if they sense that a predator is nearby.

Despite all those legs millipedes are rather slow-moving in comparison with similar critters. They are herbivores and therefore have no need to chase prey, preferring to spend their time burrowing through the leaf litter and chomping on the decaying vegetable matter that is highly unlikely to run away. This lack of speed does put them at a disadvantage when escaping from predators, and so as well as employing the tactic of coiling up they can emit unpleasant chemicals such as hydrogen cyanide in order to make themselves less palatable. Despite this defence other creatures do manage to eat them; they are at risk from frogs, toads, some spiders and birds. Starlings seem to find them especially tasty - millipedes can make up half of their diet in the spring.

I have recently spotted two different species of millipede. The first, shown above, was hanging out on a shady crag close to a forest in Northumberland, at a rather higher altitude than they would usually be found. This was a White-legged Snake Millipede, a common species that can grow to about 5 cm long. The second, shown below, was much smaller, barely more than a centimetre in length, and at first glance I thought it was a woodlouse. Its very shiny body and evenly-sized segments however proved it to be a Pill Millipede, a less common species whose party trick is rolling up into a tight ball. I found it on a beach on Anglesey, not its most usual habitat by any means. It is much more likely to be found, like the others, in woodland and on rough pasture where there are more tasty dead leaves to munch on.

Too many snails?

A resident frog

The garden pond has been a source of much entertainment for me over the past year. One of the few advantages of being in too much pain to work is that I have been able to take the time to simply sit back and watch as nature has gone about its business. Our pond is only about 6 m² large and is not very deep, but there is so much going on. It has been simply teeming with life, from the alien-looking larvae and diving beetles to the much larger visiting frogs and dragonflies. Best of all has been watching the newts, from their first appearance in spring, through the frantic breeding season to their departure in early autumn.

Back in the spring the pond was in a sorry state. It was still full of creatures, but these were scarcely visible due to the suffocating swathes of blanket weed and duckweed clogging up the water. The pond was also choked by a proliferation of decaying leaves, deposited there by a nearby tree the previous autumn. Drastic action was required.

We decided that the best way to clean up the pond was to remove huge clumps of the leaves and weed by hand, sorting through the noxious-looking mess to ensure that no living things were discarded. Before long we had a whole menagerie of weird and wonderful creatures collected in a bucket: beetles, bugs, and boatmen mixed in with the occasional amphibian. It was tiring but fascinating work. When we were done the pond was by no means perfect, but looked significantly better. We returned the creatures to their home and waited for things to settle out.

One of the newts I found in the mess of leaves

The duckweed had been conquered and the bulk of the leaves removed, but things were still not right. Despite our best efforts, the blanket weed was still there. The problem with blanket weed is that it grows, and it grows fast, expanding at a quite frankly terrifying pace on hot days. It had to be removed, but how? Luckily, inspiration struck and I devised a cunning approach to this: using a broom to simply sweep out the weed. Its green fibrous tendrils stick readily to bristles, meaning that with just a few minutes work the pond could be made much clearer. However, if even the smallest bit was left this would expand rapidly and the next day the pond would need to be 'broomed' again.

We had discovered one good weapon, but we needed to open up another front on which to attack the masses of blanket weed. The broom was a mechanical approach, and so perhaps it was time to attempt something a little more biological. We headed off to the garden centre and returned proudly wielding a water-filled bag containing seven snails. We crossed our fingers and hoped that these would be hungry molluscs, eager to chomp down every last vestige of weed.

At first not a lot happened. The pond still required regular brooming, and we rarely clapped eyes on its newest inhabitants. But then, one day, the blanket weed was gone. The water was crystal clear; we could see everything. And everything included one hell of a lot of snails. They were everywhere, not a single patch had been left uncolonised. They came in all sizes, from the barely perceptible to those several centimetres long. It was a remarkable transformation.

It is of course good to be rid of the blanket weed, but we are now wondering if we have simply substituted one bane for another. Can such a huge number of snails be healthy? Will they naturally regulate their numbers in a sensible fashion, or will there be a population explosion followed by a mass death as the pond is drained of resources? Will their excrement make the pond too toxic for other creatures? Troubling questions indeed.

Friend or foe?

Deciding that no harm, and potentially some good, would be done by a little intervention, I decided to remove some of the snails. Just working from one corner I scooped out about fifty and put them in a bucket along with some weed and sediment for them to munch on. The places these had occupied were quickly filled by others, and when I returned a mere quarter of an hour later it was impossible to tell that I had taken any out.

And now I have a new dilemma. What do I do with a bucket full of snails? I could try to sell them back to the garden centre, thus making a huge profit, but I'm not sure they'd be accepted. I could try and fob them off on neighbours with ponds, but they probably have plenty of snails of their own. I can't put them in the river as we can't tell for certain what type of snails they are, and we don't want to risk harming the ecosystem there. I need a plan, and I need one fast as I doubt snails enjoy living in a bucket. Any ideas?

That's a lot of leg!

I found this creature on the outside wall of the house yesterday and thought 'surely that amount of leg can't be necessary?'! The little critter is a harvestman, a type of arachnid that differs from spiders as its body comprises only one segment; the head, thorax and abdomen being melded together. It also possesses a mere two eyes as opposed to the spider's eight, and can't produce the silk needed to make webs. Birds are one of the harvestman's main predators, but to help deter them it can secrete a substance from the base of each front leg that smells really bad (if you happen to be a sparrow or a blue tit). It also relies on raw speed to help avoid becoming another creature's next meal - enormous legs and minimal body weight come in handy for this! Interestingly, it sheds its exoskeleton every ten days or so, like a snake shedding its skin. Harvestmen are normally nocturnal, but nonetheless it is still quite possible to see them out and about during the day. If you do spot one, try to resist picking it up as if you do, one of its legs will probably fall off.

Spiders, spiders everywhere!

I like creepy crawlies. I'm not the kind of person who will run a mile if an insect scuttles past; I’m much more likely to pick it up and inspect it more closely. So yesterday I decided to wander around the garden and see how many spiders I could find. And I can conclude that they are absolutely everywhere. I can also conclude that they are not that bright, as several seemed to go to huge amounts of effort to build beautifully-crafted webs directly behind those of other spiders, thus guaranteeing that no flies could possibly come their way. Many more decided to set up home on the doors of an old shed, piling layer upon layer of sticky yarn over the door handle and hinges. Again, a position where catching bugs is unlikely.

In fact, they seemed to be making such a concerted effort to prevent the shed from ever being opened again that it left me wondering if there’s something inside that the spiders don't want us to see. Maybe they're not so stupid after all...