Weeds & Beneficial Predators
Strategies to aid in reducing insect attack organically.
Weeds can be a valid aspect of organic garden design by providing a refuge for insect predators. These beneficial insects can help rid the garden of pests.
By allowing some weeds to flourish and avoiding monocultures we can go a long way to fighting that great bane of organic growers – insect pests. One of the first things to do is to develop a rich diversity of plant life in the garden to encourage an eco-system that supports beneficial insects.
A beneficial insect-friendly environment, through developing an sustainable ecological niche, allows the gardener to use insects to fight insects – bugs vs. bugs..
There are three types of beneficial insects
- insects that prey on others that damage plants
- insects that are parasitic – they lay their eggs on or in other insects or other insects’ eggs. The eggs hatch and the larvae eat their way out.
- Other insects are beneficial as pollinators. Bees are the obvious example but ants and moths are also pollinators.
Welcome lacewings, for example, to your garden as their grubs attack and eat a variety of insects including caterpillars, scale insects, and aphids. Some ladybirds prey on garden pests.
Many predator wasps lay their eggs in scale insects, and whitefly nymphs and moth eggs. When the eggs hatch, the larvae eat the host. Later they emerge, mate and lay more eggs thus continuing the cycle
Gruesome but useful..
To protect our predatory lacewings, parasitic wasps and the pollinators, one must be careful of spray use. Even ‘organic’ insect sprays applied at the wrong time could damage the population of beneficial insects. Usually, this entails minimizing spraying by using spot, rather than general, spraying and spraying in the evening.
If we try to encourage these useful insects, we should have less bother with damaging insects. Insects that will attack others (predate) are actively encouraged by simply allowing some area of mixed wild plants to survive as an insect haven.
A weed patch allows a place for the predators to seek refuge when needed, a place to retire to when sprays are being used. It is like a baron’s castle from which they sally forth to do battle for us.
Biological control with predatory insects will sometime mean that some (allowable) species need to be sourced from a breeder because their numbers have been depleted or because they are not native to the area. Advice needs to be sought from the supplier as to the suitability of the introduced insect.
A mixed culture is suggested rather than a monoculture which should be avoided as being the antithesis of a predator friendly garden. In the home garden, a monoculture might occur when a crop (vegetable or plant) is grown in the same place years after year. This allows insect numbers to build up as well as soil borne diseases. If a whole bed is planted out to a single crop – Cabbages – and all is cleared away around the bed, this, too, could be considered a monoculture. In the home garden a monoculture often occurs because the same flowers are planted year after year in the one bed
Leaving an edging or a patch of thickly growing weeds and allowing them to self-seed and maintain themselves, creates a sanctuary for some beneficial insects. If this is too untidy, consider inter-planting and companion planting to create insect buffer zones.
