Insatiable caterpillars
How to protect your fruit trees from the winter moth in autumn

The caterpillar of the winter moth hatches in spring, pupates in summer and, as an adult, goes in October to search for a female willing to mate
©Andi Edwards/Getty Images
Before temperatures drop below zero, most butterflies hibernate. But not the winter moth: the pupae of the butterfly hatch between October and November, usually after the first frost, and mate. In the following spring, their caterpillars prefer to eat young buds, leaves and flowers. The damage is immense.
The name of the winter moth comes from the fact that the pupae hatch at low temperatures and the feeding technique: so as not to be disturbed during their meal, the caterpillars spin themselves between the leaves. A distinction must be made between the small winter moth (Operophtera brumata) and the large winter moth (Erannis defoliaria) – the larger butterfly is less often found in gardens and thus causes significantly less damage. For this reason, this article is devoted to the small butterfly, whose caterpillars have a big appetite: their menu includes not only fruit trees (preferably apple, pear, cherry and plum), but also ornamental woods such as maple and linden. How you can quickly recognize an infestation by a winter moth and what you can do about it is summarized below.
The life cycle of the small frost moth
The winter moth is a small butterfly with a brown coat. Unlike the females, only the males can fly. Both hatch when the first frost sets in – around mid-October. After mating has taken place, the females lay up to 300 eggs near buds in the tree bark. The eggs are green at first and turn orange to red over time. When spring arrives and the first buds open, the larvae of the winter moth hatch and go in search of food. Their method of locomotion is unmistakable: they only have “feet” on their abdomen and at the end of their bodies, which they pull together like a kind of cat’s back and push apart again in order to move forward. After the Caterpillars When they have filled their bellies between April and June, they descend from the affected trees to the ground on a thin spider’s thread and pupate underground. The pupae remain there until late autumn, before they hatch as adult winter moths and a new life cycle begins.
Combating winter moths: These methods help
If you discover the caterpillars of the winter moth in spring, it is too late to take preventive measures. In this case, it makes more sense to fight the moth directly. On the one hand, you can use special preparations against butterfly caterpillars that contain the active ingredient Bacillus thuringiensis (a bacterium). Sprays is applied to the affected areas and is absorbed by the caterpillars when they eat flowers, leaves and buds. However, only use the preparation when the outside temperature is at least 15 degrees. Before this, the offspring of the winter moth are not so hungry and are not actively looking for food. Or you can use alternative products to combat the winter moth that contain other active ingredients – for example, neem oil or indoxacarb.
Another way to combat the winter moth is to use so-called glue rings. What exactly this is and what you should look out for is explained in the next section on preventative measures.
The winter moth targets almost all fruit trees, but also finds some ornamental trees tasty
© yands / Getty Images
How to prevent further infestation in the future
To prevent the small winter moth from attacking your fruit and ornamental trees, you can take preventive measures – for example, by encouraging the moth’s natural predators: Great tits can eat hundreds of caterpillars in just one day. To attract them to your garden, you should use suitable Nesting boxes Another possibility is to stop the flightless females, who have to climb up the trunks to attract the flying males. To do this, attach special Glue rings as close as possible to the trees and to all support posts and directly adjacent trees. Replace them if they are dry or damaged. Or use Caterpillar gluewhich you apply directly to the bark with a brush. In both cases, the female winter moth sticks to it and no mating takes place.
Important NOTE: Remove the glue rings again in spring to avoid endangering beneficial insects.
Source: My beautiful garden
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