There are various different types of biological pest control that you can buy online from mail order specialist suppliers; these biological controls include things like nematodes for slug control, ladybird larvae which will then hatch in your plot to help keep aphids down, parasitic wasps and bacteria powders like Bacillus thuringiensis to help prevent caterpillar damage to brassicas.
This kind of control can be used in organic gardening, and is often an effective way to keep pests at bay without using chemical pesticides. Essentially, you are introducing natural predators to your plot to prey on pests . In general, they are a good alternative to things like slug pellets and sprays.
In our opinion, these options are great for market gardeners growing on a fairly big scale. For the home grower, however, we’re not sure they are very necessary. If you can try and introduce plenty of wildlife by planting lots of different types of flowers, including wildflowers, then you probably won’t have huge problems with many of the pests. You will create a natural habitat for them to enjoy – and if you build a few bug hotels and friendly places for creatures to over-winter, then they will be likely to stick around on a more permanent basis. You might have to accept a few losses, but on the whole you can improve things so that nature does much of the pest control for you.
Of course, you will still find some pests – Slugs and snails are almost always unwanted, and it can be tempting to use nematodes. Likewise, caterpillars on brassicas are almost inevitable, even when you use good netting. Still, on a small home plot level, it is easy enough to keep on top of these by picking them off during regular pest-patrol checks, and we think it’s okay to let nature enjoy some of your crops.
For those who are growing on a larger scale, if you did want to find out more about biological pest control, the RHS website is a good place to start with some pest-by-pest information and recommendations for suppliers.