Carpenter ant (Camponotus ligniperda)

Size:

• Worker bees: 6 to 14 mm
• Queen: up to 18 mm
• Males: 8 to 12 mm (winged)

Look:

• Two-toned body: head and thorax blackish-brown, abdomen mostly black
• Very tall, powerful appearance
• Long legs and prominent mandibles
• Males and young queens are winged during the mating season.

Way of life:

• Forming societies with several thousand animals
• Clear division of labor between queen, workers and males
• Nests in deadwood, tree stumps, rotten beams, wall coverings or even in cellulose (experience report)
• Not wood-eaters, but wood-destroyers through hollowing out.

Reproduction:

• Swarming flight occurs between May and July in warm, windless weather.
• After mating, young queen bees found new colonies.
• The colony grows slowly, but reaches a large number of individuals after several years.
• Queens can live for over 10 years.
• Males die shortly after mating.

Nest locations:

• Tree stumps, rotten deadwood, woodpile
• Insulation layers, partition walls, wood paneling in the house
• Terraces, sheds, roof trusses
• Colonies retreat deep into structures and often remain undetected.

Nutrition:

• Honeydew from aphids, plant sap
• Insects and protein sources for feeding the larvae
• Sugary substances such as syrups, juices, sweets
• Unlike termites, they do not feed on wood, but they do use mechanical hollowing out to create their nests.

Behave:

• Primarily nocturnal
• Very shy and sensitive to noise
• Movements often calm and purposeful
• Female workers patrol in regular routes.
• Nest defense only occurs in the event of direct disturbance.

Structural damage:

• Hollowing out beams, insulation layers, wooden supports
• Wood shavings and sawdust at nest openings serve as a distinguishing feature.
• Often undetected for years, with increasing destruction

Swarming flight:

• Sudden mass appearance of winged animals indoors
• A visible swarm can cause unrest and irritation, psychological stress.

Disease transmission:

• Transport of microorganisms from wastewater, waste or soil

Building protection:

• Seal cracks, joints and gaps in the walls
• Check and seal window and door frames
• Avoid or replace damp and rotten wood.
• Seal food in an airtight container
• Do not leave food scraps or open waste containers.

Outdoor area:

• Reduce food sources such as aphid infestations
• Do not store firewood directly next to the house.
• Remove tree stumps, dead wood and heavily weathered wood parts

Behave:

• Detect and interrupt ant trails early
• Do not use your own insecticides indoors without consulting a professional.
• Systematically observe repeated occurrences

Experience with carpenter ants: Cellulose insulation as a nest

In the spring of 2025, we received a request for pest control services for a carpenter ant infestation in a detached house on the edge of a forest. The affected family had already unsuccessfully contacted other pest control companies. These companies declined to treat the ant infestation over the phone, stating that working near a forest edge was not practical for them. However, we do not accept such requests without a prior inspection.

Our technician conducted a thorough on-site consultation and inspection. He quickly noticed that the affected room had a former skylight. This was closed off on the outside with a wooden frame and covered on the inside with a wooden panel. Behind this was cellulose insulation, which the carpenter ants were using as nesting material.

Since carpenter ants shred wood, the loose cellulose was ideal as nesting material. The insulation was partially eaten away and heavily soaked at the bottom. We completely removed the affected material and vacuumed up the ants. We also applied a targeted, approved insecticide.

A significant improvement was subsequently noticeable. In collaboration with a construction company, discussions were held regarding how the affected area could be structurally secured in the future to prevent such incidents from recurring. The client then initiated the necessary structural measures.