Common cockchafer (Melolontha melolontha)

Also known as: May beetle, Maybug
GenusMelolontha (1)
SizeAdult beetle length: 20 – 30 mm (2)

Not threatened (2).

This common, large beetle often crashes into lighted windows at night during early summer (3). It is a familiar beetle that belongs to the same family as dung beetles (Scarabaeidae) (4). As it flies it produces an alarming loud buzzing noise, but it is harmless to humans (3). The ribbed wing cases or ‘elytra’ are reddish-brown in colour, and the head and the pronotum are blackish and covered in short hairs. The fan-like antennae are longer in males than females (5). The larvae are fat white grubs that typically have a curved body shape and live in the soil. They can grown up to 40 to 46 mm in length (5). ‘Chafer’ is a Middle English word which is thought to mean ‘to gnaw’. The prefix ‘cock’ is often used to signal maleness, but it may be a simple term of familiarity (6). The larvae are often called rook-worms, as rooks are said to have a particular love of both adult and larval cockchafers (3).

Widespread and common throughout much of Britain, but less common in the north (1).

Occurs in a range of habitats including gardens and agricultural land (5).

Adult cockchafers eat leaves and flowers of a range of deciduous trees, plants and shrubs but do not tend to be serious pests in Britain. The larvae, on the other hand, can be serious pests of grasses and cereals, as they live in the soil feeding on roots. They can be serious pests in gardens, nurseries and pastures, causing brown patches of grass to appear. They also attack other garden plants and vegetables (4).

Adults appear in April or May. They feed for a time, and females become mature at 10 to 15 days after emergence. After mating, females lay around 20 eggs in soft soil. A large number of females die after egg-laying, but some return to feeding and may then go on to lay a second or even third batch of eggs (5). After 4-6 weeks the larvae hatches out. It takes 3-4 years for the larvae to become fully developed, and they burrow deeper into the soil each winter to hibernate (5).

Although this species is not threatened at present, it has declined significantly and is no longer the serious pest it once was. This is thought to be due to mechanical cultivation, which kills the larvae(5).

Conservation action is not required for this species (4).

For more on invertebrates and their conservation see Buglife- the invertebrate conservation trust:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. National Biodiversity Network Species Dictionary (January 2004):
  2. Harde, K.W. (2000) Beetles. Silverdale Books, Leicester.
  3. Chinery. M. (1993) Insects of Britain and Northern Europe. Harper Collins Publishers Ltd, London.
  4. Kendall Bioresearch Services (January 2004):
  5. HYPP Zoology (January 2004):
  6. Buczaki, S. (2002) Fauna Britannica. Hamlyn, London.