It’s time to set pests aflutter
Hbrassicas – cover seedlings straight away to stop the butterflies finding them. The cabbage whites have a special sense that allows them to home in on brassicas (such as broccoli, cabbage, cauliflower and brussels sprouts). They lay eggs in clusters under the leaves. These quickly hatch as tiny green caterpillars that move on to the leaves’ surface to feed. Small though they are, they can decimate seedlings overnight if unchecked.
Fine white mesh stretched over crops helps keep cabbage white butterflies from reaching the leaves to lay their eggs. Keep the mesh taut – if it touches the leaves the butterflies will pick up on the opportunity and lay eggs.
Even with mesh as protection, it is necessary to regularly check brassica crops for any signs of eggs or caterpillars. Other options to control the larvae (caterpillars) are sprays such as Dipel. This is an organic option as it is based on a bacteria (bacillus thuringiensis) that affects caterpillars that hatch into moths of butterflies. The pesticide must be ingested so caterpillars feed for a day or two before they succumb. Squashing is a faster if more messy way of ridding the plant of these pests.
Dipel won’t harm insects that aren’t true caterpillars – such as the pesky pear and cherry slug. Often thought of as a caterpillar, this “slug” skeletonises leaves on cherries, pears, plums and hawthorn. I’ve also found the small, black, sluglike creature with its distinctive bulbous head on lillypilly foliage. It turns into a type of fly, so isn’t killed by Dipel. Instead, it can be controlled with pyrethrum or with a desiccating dust such as lime (or by squashing).