Box tree moth caterpillars have become increasingly common in the UK, causing extensive damage to gardens. These insects can completely strip a hedge or box ball plant within less than seven days, leaving behind a distinctive silvery webbing and lifeless foliage. Invasions peak between April and October.
According to the RHS: "Increasingly common in gardens, box caterpillar can completely defoliate box plants. Though relatively new to Britain, it has spread widely across England - particularly London and surrounding areas - and has reached the rest of the UK and Ireland."
Recognising a Caterpillar Infestation
If you notice unusual gaps in your plants' leaves or discover elongated, sluggish insects on the foliage, you may be facing a caterpillar invasion. Instead of using harsh chemical treatments, consider these homemade sprays as safe, environmentally-friendly alternatives.
Potent Natural Spray
Garden and plant specialists at Sai Nursery have devised a powerful homemade caterpillar-deterring spray using ingredients you likely already have. The experts advise: "For a potent homemade caterpillar deterrent, combine crushed chili, garlic cloves, dishwashing liquid, vegetable oil, and turmeric with water. Let the mixture sit for a while before spraying it generously on both sides of the leaves."
Caterpillars are put off by the pungent aroma of garlic, which contains natural compounds that these pests find disagreeable. Crushed chilli harbours compounds that aggravate soft-bodied insects. Turmeric is employed for its powerful scent and natural compounds, while vegetable oil coats foliage, making it harder for caterpillars to grip and feed. The washing-up liquid weakens caterpillars' hold and helps the mixture cling to foliage.
Soapy Spray
Horticultural firm The Little Veggie Patch Co suggests a straightforward soapy spray. The specialists explain: "One of the classic sprays in every gardener's toolkit - soapy spray - is great for aphids, whitefly, thrip and caterpillars."
Mix 1 tablespoon of biodegradable dishwashing liquid with 1 teaspoon of cooking oil in 1 litre of water. Spray over the foliage, particularly on the underside of leaves where pests often live. This mixture will keep for 1 month.
Soapy Garlic Spray
Landscaping specialists Maroochy Sand and Gravel advocate for a soapy garlic spray. To prepare this natural spray, you need 500ml of water, a spray bottle, two level tablespoons of garlic powder, and one teaspoon of washing-up liquid.
Decant water into the spray bottle, add garlic powder, then washing-up liquid. Secure the lid and shake vigorously to combine. Apply the solution to any plants showing damage, coating the affected area thoroughly. If you find live caterpillars, spray the mixture directly onto them. The specialists advise: "Caterpillars don't like the taste and the smell of garlic so this will deter them to go to another place, other than eating your lovely plants."
If the mixture settles between uses, give it another vigorous shake before reapplying.
