Fighting web moths: How to remove nests in fruit trees

Infestation
Nests in fruit trees? That’s what lies behind it – and this is how you act correctly

Although they belong to the butterfly family, web moths are anything but harmless: their caterpillars literally eat trees and bushes bare if they are not stopped, and wrap the trees with their silvery-white webs. This is how you deal with the infestation.

The moth owes its name to the webs that serve its offspring as a kind of protective wall against predators such as birds or against rain. Their “nets” are easily confused with those of the oak processionary moth. However, the caterpillars of the spider moth are by no means dangerous to humans – they are fine for fruit trees and bird cherries, willows and poplars, hawthorns and pine trees. If the infestation is not discovered, the pests eat entire trees and bushes bare. Below you will learn everything about the life cycle of web moths and how you can combat the annoying insects quickly and effectively.

The life cycle of a web moth

First the good news: The pest usually only targets a specific type of tree, which is why there are bird cherry moths (Yponomeuta evonymella) as well as apple web moths (Yponomeuta malinellus). They leave other trees alone. The bad news: Once the butterflies have laid their eggs, a real mass infestation can occur. Unfortunately, climate change has also contributed to the moths increasing in number as they prefer warm and dry areas. But they can also survive low temperatures without damage. In order to better understand the animals, we would like to take a look at the life cycle of a generation of web moths.

Depending on what type of web moth it is, the insects have their peak season between June and August: the females lay their eggs on twigs and young shoots and cover them with a secretion that is intended to protect them. Just a few weeks later, the first offspring hatch, which are responsible for the white-silvery web in bushes and trees. Once you have eaten your fill of the leaves, the caterpillars pupate in June – and two weeks later they are ready-made moths ready to mate. And so the cycle begins again: The female lays her eggs in the plant buds, where they survive until the next spring. In other words, in a year there is usually a new generation of web moths.

How to recognize a web moth infestation

Like many insects, the web moth is quite small: it measures just one centimeter. It is still noticeable because it has white-gray wings with small black dots on them. In contrast to the oak processionary moth, for example, the moth has no hair on its body. The Web moth larvae have a black head, are usually dark green to brown in color and have a black dot on each side. If you look closely you can even see fine hairs on the body.

The finished caterpillars, on the other hand, are cream-colored to yellowish and – like the adult butterfly – have black dots that are distributed over the entire body. To protect themselves from external weather influences and predators, the caterpillars create whitish webs around themselves. A sure sign that you have discovered a web moth infestation. Then it will be time to act quickly. Before your fruit trees or bird cherries, willows or poplars, hawthorns or pine trees are damaged extensively.

Fighting web moths: Here’s how to proceed

According to the Nature Conservation Association Germany e. V. you should not fight web moths with poison. The reason is simple: “Natural enemies are also affected by insect poisons.” Apart from that, it should be almost impossible to kill the caterpillars with a bee-friendly Plant protection products (based on Bacillus thuringiensis) if they have already spread their fine webs in the trees and bushes – the biocides would simply roll off them like rainwater. Instead, the better solution to avoid major damage would be to collect the animals by hand. Anyone who is disgusted by this should at least wear gloves – or cut off the affected branches and twigs including the webs instead of the individual nests.

What is important to know, however, is that if the caterpillars sense danger, they will rappel down to the ground on a thin thread in a matter of seconds. Only to climb back up the trees a short time later and continue their feeding spree. For this reason, it is advisable to lay a large white sheet on the ground in advance to collect possible runaways. Or you can bring a special one Glue ring on the tree trunk to which the animals stick. It is available ready to use with a fastening cord spray and in the tube or in Bucket for brushing on. Alternatively, you can also use a water hose to remove the webs from the trees.

A notice: Do not dispose of the collected webs and caterpillars in the compost, as the animals will spread further from there. Instead, it is better to take the cuttings to a waste yard or dispose of them (in a sealed bag) with the general waste.

Another way to combat web moths is to support their natural predators (such as birds, parasitic wasps and predatory bugs). The animals feel particularly comfortable in natural areas, which is why insect-friendly gardens are preferable. And the best thing about it is: the predators ensure that the pests cannot spread widely. And if so, we have some good news at the end: As soon as the caterpillars have pupated, the feeding feast ends. In addition, most trees usually recover from clear-cutting by the web moth – at least until next spring.

Sources: My beautiful garden, Utopia, NABU

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