Conservation corner - Burying buckets for stag beetles

A photograph of a buried bucket containing wood chippings. The Bury Buckets for Beetles project is intended to raise awareness of biodiversity in rotting wood, help monitor stag beetles and encourage gardeners to be a little less tidy.

A buried bucket. The Bury Buckets for Beetles project is intended to raise awareness of biodiversity in rotting wood, help monitor stag beetles and encourage gardeners to be a little less tidy.

In this issue, Conservation Corner presents an article from Nida Al-Fulaij, of the People's Trust for Endangered Species, on those amazing creatures known as stag beetles. Any of you who have seen stag beetles flying in the summer months will never forget them!

Following our national stag beetle surveys we now have a very good idea of where stag beetles occur in England and Wales. The next step is to monitor them from year to year to see if their numbers are rising, falling or staying the same, to see whether the beetles are doing well or struggling. Finding a way to monitor them is not easy. Some years, adult beetles can be common in one area, but there might be very few just a short distance away.

In any one year the number of adults emerging depends on the availability of suitable habitat when the female stag beetle laid her eggs several years earlier. At the end of summer, adult females look for deadwood in which to lay their eggs, and it is this behaviour that gave rise to the suggestion that we could provide deadwood for them at known sites, so that we could return regularly there to check what was happening.

The reason why stag beetles choose a particular piece of wood in which to nest and lay their eggs, rather than another piece of wood, is very complicated. The conditions they need can be so specific that, for example, in wooden posts next to one another on Wimbledon Common, each made of willow, larvae have been found in one but not the other. At a glance there will be very little to choose between them in terms of size and apparent levels of decay, but these factors, together with soil type, humidity, acidity and temperature, all play a part in whether or not various dead wood habitats are suitable for stag beetle larvae to develop and grow.

We do not know if the beetles have a preference for red or white rot, as they have been found in both. Previous research has suggested that oak was the preferred wood for females looking for somewhere to lay her eggs, since the distribution of stag beetles across the UK is similar to that of oak. However, this theory has not yet been proven, and stag beetle larvae have been found in pine.

So, we created Bury Buckets for Beetles. It is hoped that not only will this project raise public awareness of biodiversity in rotting wood, and encourage gardeners to be a little less tidy, but that we will be able to develop a monitoring scheme for this flagship invertebrate that focuses on the larval stage, instead of the short-lived adults. It is now time to ask those who initially took part to dig up their buckets this spring and report back to us whether or not there are any larvae present. At the same time we are hoping many more people will join in our project and bury a bucket for beetles, either in their garden or a park or common nearby.

It's easy to do. All you need is a strong plastic bucket with a handle, a tool for making holes in it, some woodchip and finally, lots of patience. First, take the bucket and make holes of at least 30mm in diameter (to allow the adult female beetles to pass through) at intervals all around the bucket with about 50mm between each hole. Then make a second and third row of holes allowing at least 50mm between rows.

On the bottom of the bucket make a series of drainage holes, about six in all, in a circular pattern. Place several large stones in the bottom of the bucket and then fill it with a mixture of one quarter soil from your garden and three-quarters woodchip. Make sure the two are well mixed together. (Woodchip from hardwood, which you can make from old wood in your garden, is preferable. However, if only softwood chippings, such as those bought from pet stores, are available, it is preferable to use these rather than not bury a bucket at all).

Dig a hole in your garden somewhere that is quiet and out of sight, making sure it is deep enough to get the whole bucket in just leaving the handle visible. Fill in any gaps around the edge with soil but do not pack it too tightly. The woodchip will begin rotting down and, as it does the bucket will become an increasingly attractive egg-laying site to any female stag beetles that happen to be in the vicinity. You will need to check the bucket every month to ensure that it is always full of mixture. As the chippings rot, the level will fall so you will need to top it up from time to time. To do this, use a mix of half woodchip and half soil.

Once your bucket has been buried for at least a year we will ask you to dig it up and tip the contents carefully onto a plastic sheet nearby where you can examine them and look for any larvae. Sift through the contents systematically and record all you see, comparing any larvae to our guide so that you can work out what exactly has been living in your own bucket. Then, importantly, repack the contents back into the bucket carefully, refill if necessary and re-bury in the garden so that the larvae can carry on growing into adults.

If you'd like to know more about the Bury Buckets 4 Beetles project then please see further information on the People's Trust for Endangered Species web site

Nida Al-Fulaij
People's Trust for Endangered Species

Originally published in the Amateur Entomologists' Society Bug Club Magazine

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