Propolis Screens

Propolis traps and screens are perforated or slotted sheets, mostly made of flexible plastic, which, when placed in the hive, redirect the bees' instinct to fill narrow gaps with propolis onto a removable surface. A well-chosen screen yields much cleaner propolis, free of wood shavings and paint, than scraping does. Gap width, food-grade material, flexibility and hive size are the deciding factors when choosing one.

How does a propolis screen work?

In the hive, bees seal with propolis any gaps and cracks too narrow for them to pass through; places where light, draughts and cold get in are especially targeted. A propolis screen offers hundreds of such narrow gaps on its surface. As the bees fill the gaps, propolis builds up on a sheet that can easily be taken out of the hive and cleaned.

The advantage of this method over scraping is purity: screen propolis contains no wood shavings, paint or dust, and its wax content is usually lower too. The harvesting and use steps are described in detail on the "Propolis Traps and Collection" page; this page focuses on the equipment itself.

What types of propolis trap are there?

Flexible plastic screen (grid)

The most common type. It is a bendable plastic sheet with fine gaps, cut to the inside dimensions of the hive. Once full, it is frozen and flexed, and the propolis falls off in flakes. It is light, cheap and can be used for years.

Slotted sheet

Sheets with long, thin slots instead of holes. They work on the same principle; propolis builds up in strips along the slots. If the sheet is made of rigid material, after freezing it is emptied by tapping it lightly or with a plastic scraper rather than by bending.

Side-wall and slatted panels

Panels made of closely spaced slats placed against the side wall of the hive body or at the edge of a box. In some hive types they are designed as part of the hive. With wooden slats, the propolis sticks to the wood and is harder to remove.

Metal wire mesh

Bees also coat metal grids with propolis; used wire queen excluders are a good example. But metal does not bend, propolis sticks tightly to metal and cleaning is difficult. Rusting or galvanised metal is not suitable for a food product.

What should you look for when choosing a propolis screen?

• Gap width: The gaps should be narrow enough that bees cannot pass through, a few millimetres. Gaps wide enough for bees to pass are filled over time not with propolis but with wax and comb; gaps that are too fine fill slowly.
• Food-grade material: Propolis is consumed directly or as an extract; the sheet should be made of food-grade, odourless plastic. Avoid recycled, smelly or painted plastic.
• Flexibility and cold resistance: Because the screen is emptied by flexing it after freezing, it needs to be a flexible material that does not crack in the cold.
• Hive size: The screen should fit the inside dimensions of the hive; if large gaps are left at the edges, the bees build wax there. Sheets that can be cut with scissors if necessary are practical.
• Thickness and flatness: A very thin sheet curls, a very thick one will not bend. A screen that lies flat sits properly in the hive.
• Number of spares: Keeping one spare per hive, so that a clean screen can go in when a full one is taken out, speeds up the workflow.

How do you fit a propolis screen in the hive?

1. The screen is laid over the top bars of the frames in the uppermost body or super.
2. There must be a bee space between the screen and the bars in which the bees can move around; without it, the bees build wax under the screen.
3. By raising the crown board slightly or leaving a small gap above the screen, a little light and air is allowed to reach the screen; this encourages the bees to seal it.
4. The hive roof is closed so that no rain gets in.
5. It is checked every few weeks; when most of the gaps are filled, the screen is taken out.

When should a propolis trap be used?

The most productive period is late summer and autumn, when the bees prepare for winter and seal up gaps. Strong colonies, apiaries near resinous trees (poplar, chestnut, pine and the like) and bee lines that collect a lot of propolis fill the screen faster.

Maintenance and lifespan of a propolis screen

• Cleaning: After each harvest the screen is frozen again and rubbed to remove the remaining thin layer. It is not washed in hot water; propolis softens in the heat and spreads into the gaps.
• Drying and storage: If necessary it is rinsed in cold water and dried completely; it is stored flat in a cool, dry place out of the sun.
• Lifespan: Flexible plastic screens last many seasons when used carefully. A screen that cracks, hardens or tears is replaced.
• Disease: The screen from a hive with disease is not used on another hive.

Common mistakes

• Laying the screen directly on the bars without leaving a bee space: the underside of the screen fills with wax and wax gets into the product.
• Using non-food-grade plastic or painted wooden panels: the product smells or carries foreign matter.
• Forgetting the screen in the hive during treatment or over the winter.
• Trying to remove propolis at room temperature: the screen tears and the propolis stretches.
• Mixing screen product with scraped product: the value of the clean batch drops.