Check susceptible plants frequently from spring onwards so action can be taken before a damaging infestation has developed. When choosing control options you can minimise harm to non-target animals by starting with the methods in the non-pesticide control section. If this is not sufficient to reduce the damage to acceptable levels then you may choose to use pesticides. Within this group the shorter persistence pesticides (that are usually certified for organic growing) are likely to be less damaging to non-target wildlife than those with longer persistence and/or systemic action.
- Where possible tolerate populations as cabbage caterpillars are food for many other creatures including social and parasitoid wasps and birds. Large cabbage white caterpillars are often infected with the parasitoid Cotesia glomerata, the larvae of this wasp burst out of the caterpillar and spin yellow cocoons
- Growing brassicas under fine netting or horticultural fleece can exclude adult butterflies and moths from laying eggs on the crop. Care must be taken to ensure the netting does not touch the plants or the adults can lay eggs through it
- Inspect plants regularly and pick off the pale yellow butterfly eggs, white spherical moth eggs and caterpillars when seen
- A biological control is available for caterpillars, this is supplied as a mixture of pathogenic nematodes, (sold as Nemasys Fruit and veg nematodes), suppliers of which can be found in the biological control leaflet available from the downloads section below. The longer the treated caterpillars and foliage stay wet, the greater chance of the treatment being effective, so apply during cool dull/ damp weather
If treating food plants with pesticides ensure that the crop is listed on the pesticide label and that all instructions are followed, particularly those on harvest interval, spray interval and maximum number of applications.
Plants in flower should not be sprayed due to the danger to pollinating insects
Inclusion of a pesticide product does not indicate a recommendation or endorsement by RHS Gardening Advice. It is a list of products currently available to the home gardener
- Organic contact insecticides containing natural pyrethrins (e.g. Bug Clear Gun for Fruit & Veg, Neudorff Bug Free Bug and Larvae Killer) can give good control of cabbage caterpillars. These pesticides have a very short persistence and so may require reapplication to keep the insects in check. The organic pesticides are not restricted in number of applications and could be used up to one day before eating the produce
- More persistent insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer) and cypermethrin (e.g. Py Bug Killer). Two (in some cases three) applications of cypermethrin, deltamethrin or lambda-cyhalothrin can be used per crop and there is a 7 or 14 day harvest interval
Pesticides for gardeners (link downloads pdf document outlining pesticides available to gardeners)
Biological control suppliers (downloads pdf document)