vegetable patch management
pest control
DEFEND - Snails B
fermented sugar traps (beer traps)
Illustration of a fermented sugar trap pot
Cutaway section of a fermented sugar trap.
The smell of fermented sugar is a very strong attractant for slugs and snails and the alcohol it produces is reasonably poisonous to them. If you place a bowl of fermented sugar amongst your vegetables then slugs and snails will be drawn to it to feed. They become drunk and end up drowning in the mixture.  Fermented sugar can be in the form of beer (which is largely made up of fermented sugar) or you can make your own fermented sugar mixture.

To make a mixture of fermented sugar add one or two tablespoons of sugar and one teaspoon of dried yeast to about 300ml of water. Stir the mixture and poor into a bowl (as described below).

Building your own fermented sugar trap
Photo of a sugar trap pot
Fermented sugar trap with a plastic pot as a cover. Note the brick on top of the pot to stop the pot being knocked over.

Photo of a commercially made sugar trap
Commercially available snail traps (one with it's lid removed). They make ideal fermented sugar traps.
A. Place a bowl in a small hollow in the soil so the lip of the bowl is at ground level. Dessert or cat food bowls make ideal beer traps.

B. Fill the bowl with fermented yeast.

C. Cover the bowl with an upturned container, such as plastic pot, bucket or ice cream tub. Either cut holes at the bottom of your upturned container or place it on a couple of pieces of wood, so slugs and snails can get at the fermented sugar. The upturned container is to keep rain or sprinklers from diluting the mixture. The fermented sugar mixture should be replaced every two or three weeks with a fresh batch.

commercially available traps
There are also purpose built traps available that are ideal for fermented sugar, but while they are convenient they are fairly expensive.

The trap in the facing photograph can be bought by mail order from Diggers Seeds.

drawbacks of fermented sugar traps
There are two main drawbacks with fermented sugar traps.  The first is that they are pretty labour intensive to maintain properly.  The mixture has to be regularly replaced and the bowls cleaned out.  The second is that they are more effective against small slugs than large snails.  I suspect that some large snails simply treat fermented sugar traps as a local pub, going there to fill up and staggering away at the end of the night to sleep it off.  I rarely find large snails in the traps, though I am sure they visit them regularly.

These days I rarely use fermented sugar traps, preferring to use the hand removal method, cover traps and iron phosphate pellets instead.