Creating a limestone bank for butterflies

25 August 2013

It’s always nice when something you plan works out well, and I’m pleased with the limestone bank we built in the garden last year.

The inspiration for it came from Jan Miller-Klein’s book “Gardening for butterflies, bees and other beneficial insects” (http://www.7wells.co.uk/index.asp). In it, she recounts how she created what she termed a “moraine garden” in order to introduce the sort of poor quality, alkaline conditions that some wild flowers need.

We have difficulty doing much with one side of our garden, as it was a rubble roadway for lorries for some 30 years, and when the land was sold back to our property, it seems all the did was shove down a bit of topsoil over it, meaning that strip is topped by a mixture of soil and (lots of) rubble, under which is compacted subsoil. Most things planted there tend to go a very funny colour, I guess because some nutrients are locked up by the compactions, and refuse to grow for a couple of years, after which they either get going or expire.

The bank under construction

We started making the bank by putting down a membrane, to discourage the bindweed, though I had some concerns that it might stop some of the plants putting their roots down deeply enough: a problem which doesn’t seem to be occurring. On top of that we put whatever rubble we could lay our hands on, including some dug out of the garden and a contribution of broken tiles from next door. We then bought some limestone chips and some limestone “dust” to make the top layer. One thing we rapidly learnt was that fine limestone, once wetted, sets very hard! Planting the wild flowers I grew from seed in the greenhouse was an interesting experience: I’ve never had to use a hammer and chisel to plant something before!

I’ve so far planted kidney vetch, harebells, bladder campion, bird’s-foot trefoil, rock rose, black medick and (recently) field scabious. None of them had any more nutrients on planting than the soil they were grown in, but they are all flourishing. They are getting a bit too rampant in places, actually, which is amazing.

Limestone bank in flower. Yellow in foreground is kidney vetch, while the yellow behind it is bird’s-foot trefoil. The white is bladder campion, and in the foreground you can just see the blue of a harebell.

My reason for creating the bank was to make use of a difficult area, allowing me to grow some of the limestone-loving wild flowers I think are very attractive. There was always the vague hope that a butterfly or two would be attracted: most of the Blues like plants like this. Most Blues would not be found in a garden, but the Common Blue was always a possibility, and one male actually turned up yesterday and found the bank. Whether a female will find it and lay eggs is considerably more dubious, not least because these butterflies don’t just need certain plants, they need ants as well, with which they have a symbiotic relationship: the caterpillars produce a sweet liquid which attracts the ants, and the ants provide some protection to the caterpillar in return (with some species the ants even take the caterpillar into their nest, where it eats the ant grubs!). I have seen black ants on my limestone bank, but goodness knows if they are the right ants.

Common Blue – background shows the limestone bank

So, the bank has done its job and allowed me to grow some attractive flowers and they have attracted a Common Blue. Whether I’ll ever get them breeding remains to be seen, but it’s fun to hope. It is very possible I’ll get some moths using the plants for their caterpillars – my challenge will be in spotting them.

Which buddleia do butterflies prefer?

17 August 2013

I’ve spoken in a previous article about the buddleia trial going on in Dorset and the first year results.  This suggested ‘Dartmoor’ (bright purple, huge flower heads), ‘Autumn Beauty’ (Lavender colour, late flowerer) and ‘White Profusion’ (white!) were top as far as the trial had gone at that point, though as all the bushes in the trial were not fully mature, this may change. What I didn’t discuss, however, was the impact of where they are planted.

Butterflies need warmth to function: that’s why you so often see them sitting on paving stones, walls etc: they are soaking up the heat from whatever they are sitting on, plus the rays of the sun (if it’s out) directly. Many of the species in Britain are at the far northern edge of their natural range, so they don’t always find the warmth they need, though it is possible there are some changes underway due to climate change. The impact of this on their choice of buddleia is as simple as whether the bush is in the shade or in the sun.

Six Peacocks in the sun on buddleia Weyeriana.

This has been being brought home to me recently by watching the butterflies on two buddleias I’ve got close together. Usually, I’d say that they would prefer ‘Lochinch’ (lavender-coloured flowers set off nicely by rather more silvery leaves than usual) to Weyeriana, which is pale orange – see the article I did on it back in April. However, my Weyeriana is now very tall – 12-15′ (4m+) I’d guess, so it’s getting sun for most of the day, especially on its top flowers. the photo above illustrates this – it isn’t a particularly good photo, because I was pointing the camera way above my head and into the light.

‘Lochinch’, by contrast, is in shade for quite a bit of the day, as you can see below, thanks to a laurel hedge becoming rather over-enthusiastic. The results are obvious: I’ve counted up to nine Peacocks, six Red Admirals, two Commas and numerous Whites on the Weyeriana simultaneously, while at the same time there were only 2 Peacocks, 2 Red Admirals and the odd White on the ‘Lochinch’.

Two Peacocks in the shade on buddleia ‘Lochinch’.

So – if you are thinking of planting a buddliea, or another buddleia (and please do), it need to be in the sunshine – or let it grow very tall, but then don’t expect to be able to take good photographs of the butterflies enjoying it!

Do bees and butterflies like onions?

9 August 2013

There are quite a few ornamental plants in the onion family which attract bees and butterflies, usually called alliums. These come mainly in shades of pink, purple and white, and with a range of flower head sizes. The attraction for insects is that there are a large number of flowers all together in one flower head, meaning they don’t have to travel far to find the next sip of nectar.

The one I’ve got out at the moment – it’s going over, but still attracting the bees – is one known by several common names, including round-headed leek, round-headed garlic, and ball-head onion, but it’s Latin name is allium sphaerocephalon. It is  useful for being later flowering than most, and is cheap to buy and easy to grow. I’ve seen a Peacock butterfly on it a few times recently, but it is mainly drawing the bees.

Bees on allium sphaerocephalon.

I think the pair on the left are white-tailed bumblebees. There are two different bees on the allium in the right-hand photo; the one at the top look like a red-tailed bumblebee; the other one is something else! Either a honey bee or a solitary bee, I guess – do send me a comment if you can identify it.

Most alliums are out a bit early in the year for there to be a large number of butterflies around, but back in 2009 we had a large influx of Painted Ladies in May.

Painted Ladies on alliums

The one on the left is on allium christophii (I think!) – they have huge flower heads, especially in relation to their height, which is only around 12″ (30cm); actually, I think they are a bit out of proportion and I won’t plant any more, but they do make very impressive seedheads. The butterfly wasn’t complaining, anyway: it spent ages working its way across and round this head of flowers. The Painted Lady on the right is on an allium you might well have in the garden: allium schoenoprasum, better known as chives. If you look at the two photos, the only real difference between the flowers is how many there are on the head and how open the petals are, other than that, you can easily see they are related.

So my answer to the question in the title of this post: “Do bees and butterflies like onions?” seems to be yes! But one question for the bee keepers among you: does nectaring on alliums produce onion-flavoured honey? Don’t think I’d fancy that on my toast.

Left holding the caterpillars

4 August 2013

I said in the last blog article that I’d tell you about the further link in that blog to butterflies, and that the clue was in what Charlotte was holding. Charlotte, by the way, was naturalist Charlotte Uhlenboek, more usually know for her work on chimpanzees. What she was holding in the photo were Peacock caterpillars.

The people making that short bit of film wanted to show the life cycle of the butterfly, and managed to get hold of a web of Peacock caterpillars: these caterpillars are very gregarious, and when they are small, they spin a web of silk round the area of leaves where they are feeding, as protection against predators. As they get older, they go it alone, and the colony spreads out, no longer protected by the web; by this stage they have spines, so they have an alternative defence against predators. Charlotte duly did her bit to camera with the caterpillars on her hand, the filming finished and the crew departed – leaving me with the caterpillars.

They were still quite small at this point, so I didn’t feel able to just put them out on their food plant – stinging nettles – but kept them in a container and fed them. This became quite an onerous task as they grew: they eat a lot, and a corresponding amoung of “frass” (butterfly poo) comes out the other end, meaning a lot of clearing up. I did eventually let some go when they were a good size, but I kept some to see them go through the next stages.

Peacock caterpillars starting to pupate

The filming was on 16 June, and the photo above was taken on 25 June, as the ones in captivity started to pupate. You can see how the caterpillar attaches itself to something – in this case the lid of the container – by silken thread. They hang there for a while, then curl up, and the transition to pupa begins.  On the left you can see a fully formed pupa.

Peacock pupae and emerging adult butterflies

On 8 July, they started hatching out into adult butterflies, as you can see above. One of the butterflies is still clinging to its pupal case; when they first come out their wings are crumpled and it takes some time to pump them up into functioning wings. The darker pupa you can see at the back is probably one soon to hatch – as the time draws near, you can sometimes see the pattern of the wings within the case.

Adult Peacock on buddleia

I never did get a decent photo of one of the adults, but here’s one from another time to remind you what this beautiful butterfly looks like.