Over the last couple of weeks we have seen an explosion in the sale of Xentari, the biological control that kills the box moth caterpillar. It's good to know that people are discovering that these caterpillars can be easily, safely and inexpensively killed. We stock Xentari in our 3 Dublin shops (Monkstown, Clare street & Dundrum) and also sell it online. These pesky caterpillars gobble up the leaves of box plants, leaving the plants web-covered, skeletal and denuded of leaves. Anywhere we go in Dublin we see plants that have been partially or fully trounced by these creatures. It's a real shame. But if a plant has been attacked by the caterpillars, all is not lost. The leaves have been eaten, but they can grow back. This explains why we are also selling so much specialist box fertiliser.
The caterpillar hasn't yet made it to all parts of Ireland, but wherever you are on the island, you should be prepared. It's only a metter of time...
If only people were aware of how easily it is treated. Xentari is a safe, non-chemical treatment that can be sprayed onto the foliage. It only affects caterpillars and is safe for birds and wildlife. When a caterpillar eats one of these leaves, it dies. Xentari stays active on the foliage for up to two weeks. After periods of heavy rain it may need to be re-applied. One box contains 5 sachets, each sachet dilutes to 3 litres and 3 litres treats up to 30 square metres of plants. At €27.50 per box of 5 sachets, that's 5 substantial treatements, more than enough for a year for most gardens.
It's important to get the Xentari inside the plant as well as on the outer leaves.
Also important is the timing. The first season of caterpillars will be mid to late March into mid May. As soon as you see any changes in your plants, including stuck-together leaves or bare patches, apply the Xentari. The second season will be in July or August, when larger caterpillars will appear. And the third season will be in September.
Keep in mind that if you stay on the case and apply the Xentari when caterpillars are active, you will have few (if any) caterpillars the next time around, meaning that task will be easier if you do it regularly and at the right time.
The caterpillars get into your box hedging as moths. The moths lay eggs on the underside of leaves, wrapping a pair of leaves together with a silken thread. If you have the time (and the patience) you can check over your box plants, pinching off these cocoons and destroying them.
Some people like to trap these moths using a pheromone trap. A pheremone trap hangs from a tree or bush, attracting the male moths and thus preventing the reproductive life cycle.
Box (Buxus sempervirens) has been a key plant in gardens for hundreds of years. Its lovely fresh leaves, its compact form and its ability to be clipped have made it an important evergreen hedge, the basis of parterre gardens, knot gardens and topiary. It would be a real shame if we let this invasive caterpillar get the better of it.
