Caterpillars – Identification and Control

Caterpillars are another common bug found in the garden and can cause serious damage if left untreated. The Cabbage White butterfly is the most common culprit in vegetable gardens. Butterflies and moths lay clusters of tiny, pale yellow eggs on the underside of leaves, which hatch into caterpillars after around 10–14 days.

Once hatched, caterpillars feed on the host plant and leave behind dark green or brown droppings. They come in many different colours and some can even be hairy (best not handled — as I found out when my sister once ended up with tiny spikes embedded in the palm of her hand!). Butterflies and moths appear in many shapes, sizes and colours, so if you see them flying around your garden, it’s very likely there are eggs nearby.

---

Symptoms

• Small holes appearing in leaves that gradually become larger

• Dark green or brown droppings found on or near affected leaves

• Rapid loss of foliage, sometimes leaving plants stripped bare

• Severe damage occurring in a short space of time

• Most commonly found on brassicas such as cabbages, cauliflowers and sprouts

---

 

Control

Check the underside of leaves regularly, where you’ll often find yellow, oval-shaped eggs laid in clusters, although sometimes a single egg may appear on its own. These can be scraped off easily with your finger and washed away.

If you spot baby or adult caterpillars, pick them off by hand and place them in a bowl of soapy water — or, if you prefer, feed them to your resident garden birds. If numbers are high, a biological treatment such as Dipel is recommended. This should be sprayed thoroughly over the plants, including the undersides of leaves and any curled foliage. Caterpillars digest the treatment, which poisons them, and they will die after around 4–5 days.

Dipel is harmless to plants and other beneficial insects working in your garden. Sunlight naturally breaks down any remaining residue, so reapplication may be needed if caterpillars persist. Sticky traps can also be useful for catching other insects around affected plants.

---

Handy Tips to Manage Caterpillars

Prevention is always better than cure. Using butterfly netting over crops can help prevent butterflies from laying eggs. If netting isn’t possible, regularly check plants and remove eggs as soon as they appear.

Placing bird feeders in your garden will help attract birds, which are natural predators of caterpillars and can significantly reduce numbers. Avoid spraying plants on very sunny days, as this can scorch the foliage.