Hello, we are inundated with white butterflies and the caterpillars are shredding my cabbages and other related plants! Derris dust doesn't seem to do a great deal. I have been chasing them with fly spray, trying to whack them with an electronic fly swat, and put plastic white butterflies out, to no avail... any other suggestions? Thanks.
Hi Sarah, it is so disheartening when crops are destroyed by insect pests. Covering your crops with a fine insect mesh available from garden centres and hardware stores, this won't completely stop the caterpillars but helps minimise the damage. Try digital control, when you see the caterpillars or caterpillar damage, hunt them down and remove them and feed them to the chooks or squish them. A pyrethrum based insect spray is effective against caterpillars, avoid spraying when bees are foraging, spray early morning or late afternoon. Some people find crushed egg shells sprinkled around plants a deterrent, others find cut-outs of caterpillars using a stencil and ice cream container lids work as well and some use garlic sprays. Plant earlier in the season, depending upon conditions, and hopefully the plants are well established before the caterpillars do the worst of their damage. There are natural caterpillar sprays with an active ingredient bacillus thuringiensis that control caterpillars effectively available from garden centres and hardware stores. Make sure all infested plant material is removed from the garden and burnt or disposed of, and not composted. If the plant material is composted, it gives the caterpillars somewhere to hide over the winter and the cycle starts all over again. The Tui Team.