Small signs, big questions: what small round holes in wood or paper can tell us

Small, round holes in a wooden frame, a piece of furniture or the pages of a book are among the most recognisable signs of past insect activity. Anyone who works with collections has probably come across them. But what do they actually tell us, and what don't they tell us?

What they may indicate

These holes are often associated with wood-boring insects, such as the common furniture beetle (Anobium punctatum). The larvae develop inside the material and, when the adult insects emerge, they leave behind the small holes we see on the surface. In other words, the holes mark where adult insects emerged from the material.

Old or active?

Holes alone don't tell us whether the problem is still active. An object may carry holes from insect activity that ended long ago.

Some signs are worth investigating more closely:

• Fresh, pale frass (a fine powder) near the holes or below the object;
• Newly appearing holes, which may become noticeable when an object is checked regularly.

Even so, these are signs to investigate, not conclusions. They call for careful inspection rather than assumptions.

Assess before treating

That is why, in integrated pest management, we assess before treating. Several elements help decide whether intervention is needed and which option is most suitable for the materials involved:

• Identifying the insect, since different species have different behaviours and implications;
• Monitoring, to understand whether there is current activity;
• Looking at the condition of the object and its surroundings, including the materials, their condition and the space where the object is kept.

If treatment proves necessary, the choice of method depends on the materials and the situation. In some cases, non-chemical options such as anoxia may be considered, after assessing whether they are suitable for the object in question.

Have you come across these marks?

If you have found these marks in your collection, our team can help with inspection and monitoring. At EXPM, integrated pest management is one of our areas of work, alongside preventive conservation and consultancy, anoxia treatments, training and conservation materials.

To find out more about our work, visit expm.com.pt, explore conservation materials at expmstore.com, or contact our team to discuss the needs of your collection.

Keeping History Alive.