Cockchafer (Melolontha melolontha) – Identification, Life Cycle and Control

The Cockchafer (Melolontha melolontha), also known as the May Bug or May Beetle, is one of Britain’s largest and most recognisable chafer beetles. Adults are particularly noticeable during late spring and early summer, when they emerge from the soil and begin flying around trees, gardens and outdoor lighting.

Cockchafers have sturdy brown bodies, distinctive fan-shaped antennae and an unusually noisy, sometimes clumsy flight. Although adult beetles can appear alarming when they fly towards windows or enter homes, they do not bite or sting and are not considered a significant health risk.

Their larvae, commonly called white grubs, spend several years underground feeding on plant roots. Large populations can damage grassland, crops and garden plants, although cockchafers are not usually the main cause of chafer grub damage in British lawns.

Understanding the difference between adult cockchafers and their underground larvae is important when assessing a possible infestation. Youngs Pest Control provides professional pest identification and control advice for homes and businesses throughout Greater Manchester, Cheshire and Merseyside.

Cockchafer – Quick Facts

Cockchafer Taxonomy and Classification

The Cockchafer belongs to the order Coleoptera, which contains the beetles. It is part of the family Scarabaeidae, a diverse group that includes chafers and dung beetles.

The Cockchafer is sometimes confused with other chafer beetles found in British gardens. Identifying the species is particularly important when larvae are discovered in soil because not all white grubs damage living plant roots.

For further information about the species, see the Woodland Trust’s Cockchafer Beetle guide.

How to Identify an Adult Cockchafer

Adult cockchafers have several distinctive characteristics that help separate them from smaller chafer beetles.

Body Size

Adults usually measure approximately 20–30 mm in length, making them noticeably larger than many other common British chafers.

Brown Wing Cases

The hardened wing covers, known as elytra, are generally reddish-brown or chestnut-brown.

Dark Head and Thorax

The head and thorax are typically darker than the wing cases, often appearing black or very dark brown.

Fan-Shaped Antennae

Cockchafers possess distinctive antennae with flattened segments that spread into a fan. These are particularly prominent in males and are used to detect chemical signals.

White Abdominal Markings

Small white triangular patches are visible along the sides of the abdomen.

Robust Body Shape

The body is broad, sturdy and oval-shaped, with strong legs and a protective exoskeleton.

Noisy Flight

Adult cockchafers are known for their loud, sometimes awkward flight. They may bump into windows or other objects while flying around lights.

What Do Cockchafer Larvae Look Like?

Cockchafer larvae are commonly known as white grubs.

They have thick, creamy-white bodies that curl into a distinctive C-shape when disturbed.

The head is brown, with strong chewing mouthparts used for feeding on roots and other suitable plant material.

Three pairs of legs are positioned near the front of the body.

As they develop, cockchafer larvae can become substantially larger than the grubs of some other chafer species.

However, size and colour alone may not be sufficient for identification because several beetle species produce similar larvae.

Cockchafer vs Garden Chafer

The Garden Chafer (Phyllopertha horticola) is another scarab beetle encountered in British gardens.

The distinction matters because Garden Chafer larvae are among the species more frequently responsible for damaged turf in the UK.

Cockchafer vs Summer Chafer

The Summer Chafer (Amphimallon solstitiale) is generally smaller than the Cockchafer and has a lighter brown, hairy appearance.

Both species may fly during warmer evenings and can be attracted to artificial lighting.

Cockchafers are generally larger and have more prominent fan-shaped antennae and distinctive white abdominal markings.

Cockchafer vs Rose Chafer

The Rose Chafer (Cetonia aurata) is usually easy to distinguish as an adult because of its bright metallic green colouring.

Its larvae, however, can resemble cockchafer grubs.

Rose Chafer larvae commonly develop in compost and decaying organic material, where they contribute to decomposition.

Cockchafer larvae are more strongly associated with feeding on living plant roots.

It is therefore important not to assume that every large white grub found in a garden requires treatment.

Cockchafer Life Cycle and Reproduction

The Cockchafer undergoes complete metamorphosis, developing through four stages: egg, larva, pupa and adult.

Its life cycle is unusually long compared with many other beetles, often taking three to four years and sometimes longer depending on environmental conditions.

1. Egg Stage

Female cockchafers lay their eggs in the soil during late spring or early summer.

Grassy fields, lawns and other vegetated ground can provide suitable egg-laying locations.

The eggs hatch after several weeks, depending on soil conditions.

2. Larval Stage

Newly hatched larvae begin feeding underground on suitable plant roots.

As they grow, they develop into larger C-shaped white grubs.

The larval stage commonly lasts several years and accounts for most of the insect’s life cycle.

3. Pupal Stage

After completing larval development, the insect pupates in the soil.

During this stage, the larva transforms into an adult beetle.

4. Adult Stage

Adult cockchafers emerge during late spring or early summer, often around May.

They feed on foliage, seek mates and reproduce during their relatively short adult lives.

After mating, females return to the soil to lay eggs, beginning the next generation.

Cockchafer Life Cycle Summary

Why Are Cockchafers Called May Bugs?

The name May Bug comes from the seasonal appearance of adult cockchafers during late spring.

In Britain, adults often emerge around May, although their flight period may continue into June or July.

They are especially noticeable during warm evenings when they fly around trees, gardens and outdoor lights.

Their large size and noisy flight can make them appear more threatening than they actually are.

Where Do Cockchafers Live?

Cockchafers occur in a variety of environments where suitable vegetation and soil conditions are available.

Grasslands

Grassy habitats provide plant roots for developing larvae.

Meadows

Meadows can provide both underground larval habitat and surrounding vegetation for adults.

Farmland

Agricultural soils may support larval development, particularly where suitable host plants are present.

Woodland Edges

Adult beetles may feed on nearby trees and shrubs.

Gardens

Domestic lawns and planted areas can occasionally support cockchafer larvae.

Parks

Established grassland and mature trees can provide suitable conditions for different life stages.

The species spends most of its life underground, meaning adult sightings represent only a short part of its development.

What Do Adult Cockchafers Eat?

Adult cockchafers feed mainly on the foliage of trees and shrubs.

Plants that may be used include:

• Oak trees
• Beech trees
• Birch trees
• Fruit trees
• Other suitable broadleaved trees and shrubs

Large populations can sometimes cause noticeable leaf damage, although significant defoliation by adult cockchafers is uncommon in modern British gardens.

What Do Cockchafer Larvae Eat?

Cockchafer larvae live underground and feed on plant roots.

Their food sources may include:

• Grass roots
• Agricultural crop roots
• Roots of garden plants
• Other suitable herbaceous vegetation

Feeding can weaken plants by reducing their ability to absorb water and nutrients.

Where large numbers of larvae are present, root damage may become more noticeable, particularly during dry weather or other periods of plant stress.

Can Cockchafer Grubs Damage Lawns?

Yes. Cockchafer grubs can damage lawns by feeding on grass roots, although they are not usually the most common chafer species responsible for serious turf damage in Britain.

High larval populations may weaken grass and contribute to yellowing, thinning or bare patches.

Root damage can also make turf easier to lift away from the soil.

However, similar symptoms can be caused by drought, disease, leatherjackets and other chafer grub species.

Correct identification is therefore important before selecting a treatment.

What Are the Signs of Chafer Grub Damage?

Chafer grub activity may become apparent through changes in lawn condition and the presence of larvae beneath the turf.

• Yellowing grass: Patches of turf may become pale or discoloured.
• Thinning lawns: Grass may gradually weaken where roots have been damaged.
• Loose turf: Severely affected areas may lift more easily from the soil.
• White grubs: C-shaped larvae may be found beneath damaged sections.
• Bird activity: Crows and other birds may search the soil for grubs.
• Animal digging: Foxes or badgers may disturb turf while feeding on larvae.
• Uneven damage: Affected areas may occur in irregular patches.

These signs indicate a possible soil pest problem but do not prove that Cockchafer larvae are responsible.

Why Are Birds Digging Up My Lawn?

Birds and other animals may disturb lawns while searching for soil-dwelling invertebrates.

Chafer grubs provide a food source for several species, including crows and starlings.

Where larvae are abundant, repeated digging can damage the turf independently of the feeding damage caused underground.

However, birds also feed on earthworms and other insects, so their presence alone does not confirm a chafer infestation.

Why Are Cockchafers Attracted to Lights?

Adult cockchafers are frequently attracted to artificial lighting during their evening flights.

They may gather around illuminated windows, outdoor lamps and entrances.

Occasionally, beetles enter buildings through open windows or doors.

This behaviour is generally temporary and does not indicate that the beetles are breeding indoors.

Reducing unnecessary exterior lighting and fitting suitable window screens may help limit accidental entry during the flight season.

Do Cockchafers Bite or Sting?

No. Cockchafers do not possess stings and are not regarded as biting pests of people.

Although they have chewing mouthparts, these are adapted for feeding on vegetation rather than attacking humans.

Their size, buzzing flight and tendency to collide with objects can make them appear intimidating.

However, adult cockchafers are generally harmless when encountered around homes and gardens.

Are Cockchafers Dangerous to Humans?

Cockchafers are not considered significant public health pests.

They are not known for spreading human disease and do not normally cause direct harm to people.

The main concerns associated with the species involve potential damage to plants and occasional nuisance from adult beetles gathering around lights.

In most situations, an individual cockchafer found indoors can simply be released outside.

Do Cockchafers Damage Buildings?

Cockchafers do not normally damage timber, brickwork, electrical wiring or household furnishings.

Their larvae develop in soil rather than within structural wood.

Adults may enter buildings accidentally during their seasonal flights, but they do not establish indoor breeding populations.

They should not be confused with wood-boring beetles, whose larvae develop inside timber.

Why Do Cockchafers Appear in Large Numbers?

Cockchafers can sometimes emerge in noticeable numbers when several individuals complete their lengthy underground development at approximately the same time.

Because larval development takes several years, local populations may show periodic increases in adult activity.

Suitable soil conditions, food availability and weather can influence the number of beetles emerging in a particular season.

Large evening flights may therefore occur in some years without indicating a permanent infestation inside nearby buildings.

Natural Predators of Cockchafers

Cockchafers form part of the wider food web and provide food for several animals.

Natural predators may include:

• Crows and other birds
• Starlings
• Hedgehogs
• Moles
• Foxes
• Certain predatory and parasitic insects

Soil-dwelling pathogens, including some fungi and nematodes, may also affect developing larvae.

These natural enemies can influence cockchafer populations, although they do not necessarily prevent occasional local outbreaks.

How to Manage Cockchafers in Gardens

Most cockchafer sightings do not require pest control treatment.

Adults are seasonal insects, and a few beetles flying around lights or trees are generally harmless.

Where lawn or plant damage is suspected, the first step is to investigate the cause rather than assume cockchafers are responsible.

1. Identify the Insect

Confirm whether the beetle or grub is a Cockchafer or another chafer species.

2. Inspect Affected Turf

Examine small sections of damaged lawn for larvae and signs of root feeding.

3. Assess the Damage

Consider whether the grass is being damaged by larvae, drought, disease or another problem.

4. Protect Lawn Health

Maintain appropriate watering, mowing and soil conditions to support healthy root growth.

5. Repair Damaged Areas

Where necessary, damaged turf can be repaired or reseeded at a suitable time of year.

6. Consider Biological Control Carefully

Beneficial nematodes are used against certain chafer grub species, but effectiveness depends on the target species, soil temperature, moisture and product instructions.

7. Seek Professional Advice

Where damage is extensive or identification remains uncertain, a professional assessment may help determine the most appropriate response.

Unnecessary insecticide use should be avoided, particularly where the larvae may belong to beneficial or non-damaging beetle species.

Can Nematodes Control Chafer Grubs?

Some biological control products contain insect-pathogenic nematodes that can infect certain chafer grubs.

These microscopic organisms are applied to suitable soil conditions and require adequate moisture and appropriate temperatures to work effectively.

However, not all chafer species respond equally, and a product intended for common lawn-damaging chafers should not automatically be assumed effective against Cockchafer larvae.

For detailed guidance on identifying lawn damage and biological control options, see the Royal Horticultural Society’s guide to chafer grubs in lawns.

When Should Cockchafer Grubs Be Treated?

Treatment should only be considered when the larvae have been correctly identified and are causing significant damage.

Finding a small number of white grubs in soil does not necessarily indicate a harmful infestation.

Some chafer larvae are relatively harmless, while others contribute to decomposition and wider garden biodiversity.

Where treatment is justified, the appropriate method depends on the species, severity of damage, season and soil conditions.

Professional advice can help avoid unnecessary or ineffective applications.

How to Prevent Cockchafer Problems

It is not always possible or necessary to prevent cockchafers from using gardens and surrounding green spaces.

However, several practical measures can reduce nuisance and help identify developing lawn problems.

• Monitor lawns for unexplained yellowing or thinning.
• Investigate persistent root damage before applying treatments.
• Maintain healthy turf through appropriate watering and lawn care.
• Inspect soil where substantial lawn damage is occurring.
• Reduce unnecessary outdoor lighting during peak adult flights.
• Use suitable window screens to limit accidental beetle entry.
• Avoid treating harmless beetles or grubs without identification.
• Seek advice where large numbers of larvae coincide with significant plant damage.

Cockchafers in Commercial and Managed Grounds

Cockchafer larvae may occasionally affect managed landscapes where large areas of grass or other suitable plants are present.

Sports Grounds

Root damage from harmful chafer species can weaken turf and affect playing surfaces.

Golf Courses

Managed grass areas may require investigation where unexplained turf deterioration occurs.

Commercial Landscapes

Planted areas and lawns may occasionally experience soil-dwelling grub activity.

Agricultural Land

Large populations of root-feeding larvae can affect crops and grassland.

Public Parks

Grubs may occur naturally in soil, although treatment is only justified where significant damage is confirmed.

Because several beetle species can produce similar larvae, species identification should form part of any management decision.

Professional Cockchafer Identification and Pest Advice

Suspected cockchafer infestations should be assessed carefully because adult beetles are generally harmless and not all white grubs damage plants.

Youngs Pest Control provides professional pest control services and identification advice for a wide range of insect problems.

1. Inspection and Assessment

We consider the reported insect activity, the affected areas and any evidence of plant or property damage.

2. Pest Identification

Correct identification helps distinguish cockchafers from other beetles and soil-dwelling larvae.

3. Appropriate Management Advice

Where the insects are harmless, treatment may not be necessary. Where genuine damage is confirmed, suitable management options can be considered.

4. Prevention Guidance

We can provide practical advice on monitoring, reducing nuisance activity and recognising when further investigation is needed.

Any specialist lawn treatment should be discussed and confirmed with the provider rather than assumed to be part of a general pest control service.

Cockchafer Advice Across Greater Manchester, Cheshire and Merseyside

Youngs Pest Control is a family-run pest management company providing services throughout Greater Manchester, Cheshire and Merseyside.

Our team helps homeowners, landlords and businesses identify pest problems and understand suitable treatment and prevention options.

For information about our wider services, visit our pest control services page.

Whether you have discovered an unfamiliar beetle indoors or suspect chafer grub activity in your garden, accurate identification is the starting point for deciding what action is necessary.

Frequently Asked Questions About Cockchafers

What is a cockchafer?

A cockchafer is a large scarab beetle scientifically known as Melolontha melolontha.

Is a cockchafer the same as a May Bug?

Yes. Cockchafers are commonly called May Bugs or May Beetles.

Are cockchafers common in the UK?

They occur in Britain and are most noticeable during their late-spring and early-summer flight period.

What does a cockchafer look like?

It has brown wing cases, a dark head, fan-shaped antennae and white markings along the abdomen.

How big is a cockchafer?

Adults usually measure approximately 20–30 mm in length.

Why are cockchafers called May Bugs?

Adults often emerge and become noticeable during May.

When do cockchafers appear?

They are typically active from May into early summer, sometimes continuing into July.

Why are cockchafers flying around my lights?

Adults are attracted to artificial lighting during their evening flights.

Do cockchafers bite?

No. They are not considered biting insects of people.

Do cockchafers sting?

No. Cockchafers do not possess stings.

Are cockchafers dangerous?

They are generally harmless to people, although large larval populations can damage plant roots.

What do adult cockchafers eat?

Adults feed on leaves and flowers of suitable trees and shrubs.

What do cockchafer larvae eat?

They feed underground on the roots of grasses and other plants.

What do cockchafer grubs look like?

They are large, creamy-white, C-shaped larvae with brown heads and three pairs of legs.

How long do cockchafers live?

The full life cycle takes several years, but adults generally live for only a few weeks.

Where do cockchafers lay eggs?

Females lay eggs in soil, often in grassy or vegetated areas.

Can cockchafer grubs damage lawns?

Yes, although other chafer species are more frequently responsible for serious lawn damage in Britain.

Why is my lawn turning yellow?

Root-feeding larvae are one possible cause, but drought, disease and other conditions can produce similar symptoms.

Why are birds digging up my lawn?

They may be searching for chafer grubs or other soil-dwelling invertebrates.

Do cockchafers breed inside houses?

No. Their immature stages develop in soil outdoors.

Can cockchafers damage timber?

No. They are not wood-boring beetles and do not normally damage structural timber.

Are all white grubs harmful?

No. Several beetle species have similar larvae, and many are harmless or beneficial.

Can nematodes treat cockchafer grubs?

Some nematode products target chafer grubs, but suitability and effectiveness depend on the species and treatment conditions.

Should I kill a cockchafer found indoors?

Usually not. An adult beetle can generally be released outside.

When should I seek professional advice?

Seek advice when insect identification is uncertain or substantial lawn or plant damage is occurring.

Cockchafer Identification and Pest Advice – Youngs Pest Control

The Cockchafer is a distinctive British beetle whose adult stage is mainly a seasonal curiosity, while its underground larvae can occasionally cause damage to plant roots.

Because several chafer species produce similar grubs, accurate identification is essential before deciding whether treatment is necessary.

Youngs Pest Control is a family-run company with over 35 years of pest management experience. We are fully insured and members of the National Pest Technicians Association.

We provide professional pest identification, inspections and practical pest management advice for homes and businesses across Greater Manchester, Cheshire and Merseyside.

If you have discovered unfamiliar beetles or suspect an insect problem around your property, contact our team for advice.

Contact Youngs Pest Control:

0161 776 9832

07845 815 261