Life cycle of the Oak Processionary Moth

Egg stage
Egg stage
- Eggs are laid in masses or plaques about 2cm long on high branches and twigs
- Females can lay between 100-300 eggs each year
- Egg plaques are covered with greyish scales and remain on trees during the following autumn and winter.
- First stage larvae hatch from eggs in April
- Moths will lay eggs on multiple oak trees
Instar L1 - Mid April
Instar L1 - Mid April
- Eggs will hatch just prior to bud burst;
- Caterpillars are <3cm with black heads and orange bodies;
- They feed at night and stay in the leaf buds.
Instar L2 - Early May
Instar L2 - Early May
- Caterpillars shed skin as food and temperature increases;
- The caterpillars remain in the extremities of branches.
Instar L3 - Mid May
Instar L3 - Mid May
- Caterpillars are now between 10-15mm long;
- They aggregate in large groups and have started to produce toxic hairs.
Instar L4 - End of May to Mid June
Instar L4 - End of May to Mid June
- Roughly 20-25mm;
- They start to form tents, clean and pale in colour;
- There is an accumulation of shed skin and have approximately 700,000 toxic hairs each.
Instar L5 - June to Mid July
Instar L5 - June to Mid July
- Caterpillars are now much easier to identify at roughly 30mm;
- Nests are larger and covered in silk and shed skins;
- There are clear signs of feeding damage.
Instar L6 - Late June to Late July
Instar L6 - Late June to Late July
- Caterpillars are roughly 35mm in size;
- Large, dirty nests brown in colour from shed skins, located on trunk and scaffold limbs.
Pupae
Pupae
- At ground level with grass incorporated;
- Contains a lot of excrement and shed skins;
- Remains hazardous for many years due to hairs.
Adult Moth
Adult Moth
- Moths start emerging around Mid July and all will have emerged by late September;
- Moths are nocturnal and live for only three to four days and do not feed;
- Males emerge before females and can fly up to 20km (12 miles);
- Females are seldom found more than 500m from their ‘home tree’ and are attracted to the ‘scent’ of oak;
- Adult moths are not easily distinguishable from some other species.

ISO 14001

ISO 14001
ISO 45001

ISO 45001
ISO 9001

ISO 9001
UVDB Achilles

UVDB Achilles
ARB Approved Contractor

ARB Approved Contractor
Safecontractor

Safecontractor
BASIS Amenity Assured

BASIS Amenity Assured
Constructionline

Constructionline
The Contractors Health and Safety Assessment Scheme

The Contractors Health and Safety Assessment Scheme
Property Care Association (PCA)

Property Care Association (PCA)
Trust Mark

Trust Mark
The Amenity Standard

The Amenity Standard
Forestry Industry Safety Accord (FISA)

Forestry Industry Safety Accord (FISA)
Royal Forestry Society

Royal Forestry Society
The 5% Club

The 5% Club

Life cycle

The 9 stages of life the oak Processionary Moth goes through

Egg stage

Instar L1 - Mid April

Instar L2 - Early May

Instar L3 - Mid May

Instar L4 - End of May to Mid June

Instar L5 - June to Mid July

Instar L6 - Late June to Late July

Pupae

Adult Moth

ISO 14001

ISO 45001

ISO 9001

UVDB Achilles

ARB Approved Contractor

Safecontractor

BASIS Amenity Assured

Constructionline

The Contractors Health and Safety Assessment Scheme

Property Care Association (PCA)

Trust Mark

The Amenity Standard

Forestry Industry Safety Accord (FISA)

Royal Forestry Society

The 5% Club