Stag Beetle

Pressures
Stag beetle numbers have declined since the 1940's, and their UK distribution has contracted from a large swathe of southern England and Wales. It is believed that the destruction of the beetles' key habitat - dead wood - through the ‘tidying-up’ of woodlands and parks is the prime reason for its decline, although in urban areas the impact of traffic, feet, cats and other predators are all significant. 

Life cycle
The stag beetle has a very long life cycle the majority of which is spent underground in their larval stage. They spend between three and up to seven years in the larval state. The larvae only feed on decaying wood so please do not kill them! They then build an ovoid shaped cocoon in the soil, up to 20cm below ground, which can be as large as an orange and take up to three weeks to build. Within it the larva will pupate and finally metamorphose into an adult. 

Other terrestrial beetles
The beetle that is most often mistaken for a female stag beetle is the lesser stag beetle. A large lesser stag beetle can be similar in size and shape to a small female stag beetle. However, the lesser stag is uniformly black all over with matt wing cases, while the female stag beetle has shiny brown or maroon wing cases. Lesser stag beetles tend to have a much squarer overall look. Cockchafers can be of a similar size to lesser stags and are active on warm nights in May and June, but can be distinguished from stags by their ribbed wing cases and covering of hair. 

Beetle larvae can also cause confusion. A fully-grown stag beetle larva can be up to 11cm long. They are fairly smooth skinned have orange head and legs and brown jaws. They are nearly always found in damp decayed or decaying wood below ground and can be up to 50cm down. Placed on the ground they take up a C shape. The lesser stag beetle larva is very similar, however as a general rule, the lesser larva will be found above ground in drier wood, often in great numbers. There are also often lesser stag beetle adults present nearby. 

Where
Stag beetles are still locally common in a number of hotspots such as the Thames Valley, around north-east Essex and in London. They have recently been recorded in most London boroughs, but they appear to be significantly more common in the south and west of London, in areas such as Beckenham, Dulwich, Lewisham, Wandsworth, and Richmond. 

When
Larvae emerge from cocoons in the autumn and spending the winter and spring in the soil. Adult beetles usually emerge from mid May onwards and by the end of August most of them will have died after mating. They do not survive the winter. 

Creating Habitat 

• Retain as much dead wood - logs and stumps - as possible on site - the larger the better (which helps prevent burning, vandalism or removal). If possible some of this needs to be in the shade to avoid desiccation. 
• Install a loggery at the end of the garden. Preferably build these from natural wood (do not use softwoods (conifers) or treated timber). These need to be on woodland edges where some degree of shade can be guaranteed. 
• Leave windblown trees in place, except where they pose a safety problem. 
• Make sure that most of the dead wood is lying on or close to the ground. 
• Ensure that a buffer zone is managed around large dead wood so that the soils and vegetation are protected as much as possible from disturbance. Ideally this should not be cut between May and September. 
• Avoid stump-grinding tree stumps wherever possible. 
• Identify the needs of stag beetle in site management plans, and provide particular prescriptions for management of dead wood. 
• Check the pond or water-butt during the adult flying season (May to July); they often fall in and cannot swim. If you see a beetle in the water, take it out – they often revive! 
• Try and prevent cats (or other predators) from attacking the adults during the flying season.