The easiest way to find many chafers is by looking on flowers in warm weather during the Spring and Summer. Many species like to bask and will also feed on petals and leaves.
Some species fly at dusk and are readily attracted to light such as the Burrow beetle Odonteus armiger and the Cockchafer Melolontha melolontha. These beetles are regularly reported by moth enthusiasts and moth traps can be used to the scarab beetlers advantage. There are a variety of light traps on the market (Watkins and Doncaster), some are quite expensive but you can build your own too.
Larvae are often dug up while gardening or found in a compost heap. Maria Fremlin has produced a really useful Gardners Guide to help distinguish Rose chafer and Cockchafer larvae from stag beetle larvae.
There are a number of techniques that you can use to search for scarabs in dung. The most effective are visual search, digging out tunnels, sieving and pitfall traps.
This is pretty straight forward. It simply involves finding a pile of dung and breaking it apart to look inside and find the beetles.
Digging Out Tunnels
Look for tunnels at the soil interface under the dung. These can be large enough to poke in your thumb (Geotrupidae tunnel) or as small as the width of a pencil (Onthophagus similis, Colobopterus erraticus). The beetle can be very carefully dug out with a small trowel or penknife. Often the best approach is to feel the direction of the tunnel by poking in a finger, then carefully dig out the surrounding soil. Take great care not to damage the beetle inside. We have produce a short film to show you how to do this.
Lumps of dung are placed in a sieve and vigorously shaken over a pale coloured tray. The dung beetles will drop through the holes of the sieve into the tray below. After a few moments the beetles will start to move around and be easier to spot. In hot weather beware that they can quickly fly away. It is useful to rest the sieve and contents on a second tray whilst looking for beetles in the first as some may continue to fall from the dung.
We use a round garden sieve with 1cm holes and a white lab style tray but a cat litter tray will work equally as well. Click here to view a video clip to show you how to do this.
A pitfall fall trap is a container dug into the ground so that the top is level with or just below the ground surface. A mesh grid is placed over the aperture, secured with tent pegs and a lump of fresh dung rested on top. A rain guard should be placed above to prevent the container filling with water. We use an inverted plastic plate that has three pre-made holes and prop it up with tent pegs so that it rests around 10-15cm above the trap.
Dung beetles will be attracted by the smell of the dung, fly in, land nearby, and walk towards the dung and drop into the container below.
Pitfall traps can be live or kill traps. If using a live trap, place a funnel (with he spout cut off) into the aperture. This reduces the chance of beetles flying out. Line the base of the container with 3-4 cm of sand or local soil so that the beetles can bury themselves. This is important as it reduces stress and gives them somewhere to hide from any predatory beetles that may also be caught in the trap. Live traps will need to be checked and emptied daily. Otherwise predatory beetles such as Rove beetles (Staphylinidae) will eat all the smaller dung beetles.
If using a kill trap, a preservative fluid must be used. We recommend propylene glycol which is commonly used as a food additive. It is safe for mammals and will preserve your catch well for 7-10 days. Water with a little salt added can also be used but beetles will start to decompose after 4-7 days depending on temperature. Which ever you choose, pour 3-4 cm of fluid into the bottom of the trap and add a couple of drops of unscented washing-up liquid to break the surface tension. Kill traps are not recommended on sites with rare species.
Dung beetles bury themselves to escape predation from birds and we can use this ‘dig down’ mechanism to our advantage. A Winkler extractor is often used to sample leaf litter invertebrates but works really well with sieved dung samples too. In the Winkler method, sieved samples are placed in small mesh sacks which are suspended inside a funnel shaped outer sack, usually of cotton/canvas material. A collecting bottle is situated at the base of the funnel. The whole contraption is hung from a tree branch or frame so that the base of the collecting bottle is held off the ground. Over time the dung sievings dry out and this encourages the beetles to bury through the substrate and drop into the bottle below. This can be a slow process and may take 2-3 days to collect the beetles but the majority will fall through within the first 12-18 hours.
Dung can also be immersed in water and the beetles will, quite quickly, float to the surface. This method is best used with cow dung. The dung may also float and require weighting. This can be achieved by placing some wire mesh over the dung. Beetles can be easily scooped out with a tea strainer or fine gauge kitchen sieve. Alternatively, they can be picked out by hand but this will take a lot longer, especially if the beetles are numerous.
With this method, you will only be sampling the beetles that live directly in the dung and will not usually find any that burrow beneath. Click here to watch our video guide to floatation.
Adult Stag Beetles are most likely to be found near the larval habitat of dead wood. Larvae are sometimes disturbed when moving log piles or removing dead wood. Although we would encourage that you leave dead wood rather than burning, chipping or otherwise disposing of it. Dead wood is a great resource for many insects and one that is often overlooked.
Adult stag beetles (Lucanus cervus) are often seen wandering around in May, June and July an hour or two before dusk. Males are more likely to be seen in flight than females. They are largest beetles that you will see in the British Isles and are rather spectacular. There is a strong south-easterly distribution. There is some evidence to suggest that Stag Beetles are attracted to ginger and they have been found by using a ginger root baited flight intercept trap. Larvae usually feed on the dead wood below ground.
The larvae of the Lesser Stag Beetles (Dorcus parallelipipidus) feed within dead wood above ground. Adults can be exposed in their galleries when breaking up dead wood. A word of caution though, wood can take a very long time to rot down enough to become suitable habitat for stag beetles. Destructive sampling of dead wood is not recommended as this habitat is not easily or quickly replaced. Sometimes the remains of an adult can be found by sieving material from a tree rot hole. The adults are also seen wandering about during May – July and are often mistaken for an adult female Lucanus cervus.
The Rhinoceros Beetle Sinodendron cyclindricum can be found in much the same way as the Lesser Stag Beetle. The adults are less likely to be found wandering about but are occasionally seen on the trunks of trees.
The best way to find Hide Beetles is by sieving old nest material from bird boxes especially owl boxes. Be mindful of the bird breeding season and avoid disturbing any resident birds. The best time to do this is when cleaning out a bird box in the autumn months. A local bird ringer may be happy for you to accompany them on nest box checks after the young have fledged.
Hide Beetles can also be found by sieving the contents of tree rot holes so keep an eye out for them when looking for stag beetles too. Often you may only find an elytra (wing case).
Sand dunes are home to quite a few British scarab species. The easiest way to find them is by checking in the base of a dune blow-out. The beetles are are often blown into these large hollows and are unable to climb up the steep sides. They can be difficult to spot amongst the debris but once you have a found a couple this gets easier. Be careful not to disturb loose sand so that it falls into the bottom of the blow-out as this may cover any beetles trapped there.
Many of the Sand Scarabs are nocturnal and a night time search along the dunes with a good head torch can also be very productive.