The winter moth is a pest on fruit trees, berries and ornamental deciduous trees with a destructive potential that comes very close to that of the dreaded codling moth. Biologists distinguish between the small winter moth and the large winter moth, with the two species only differing in size, but not in their life cycle and their harmful effects. The lesser winter moth has a wingspan of about 25 millimeters and is much more up to mischief in German gardens than the large winter moth with a wingspan of 46 millimeters. The prevention and control of this pest is directed uniformly against both versions, so that in the following we will only talk about the winter moth itself.
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Visual appearance and life cycle
In order to effectively combat the unwanted pest, it is important to become familiar with its appearance and life cycle. It is noteworthy that males and females differ significantly. The males are butterflies with gray-yellow to beige-brown wings and short antennae. The grey-brown females, on the other hand, are flightless and have six remarkably long, spider-like legs with which they move.
However, the actual damage to apples, pears, cherries, plums and berries is caused by the light green caterpillars. The moths begin their flight immediately after hatching during the period from mid-October to mid-December. At the same time, the females crawl up the host trees, which are not only fruit trees, but also beech, alder, oak and maple. After mating, the eggs are usually laid in the upper crown area in the bark cracks or tree wounds, where they overwinter. As soon as the first green buds appear, the caterpillars hatch and start grazing. Not only the buds fall victim to them, but also the leaves and the fruits, because they are real omnivores and up to mid-June. Then they rappel down to the ground where they pupate at a depth of about 20 cm. The next generation of winter moths hatches from the cocoons in late autumn.
prevention
One of the most effective preventive measures against the winter moth is to attach glue rings to the tree trunk. Glue rings are available from specialist retailers and are completely non-toxic. This prevents the flightless females from climbing up and laying their eggs in the crown area.
By the end of September at the latest, it is time to attach the glue rings to the tree. The 8 cm to 10 cm wide strips are made of paper or plastic and are provided with an adhesive in which the female winter moths get caught. It is important that the rings overlap and enclose the trunk tightly so that the females do not crawl under it. If the bark of the tree trunk has larger bumps that the glue ring does not completely cover, it is advisable to stuff these gaps with paper. It is essential to also wrap neighboring trees and the support posts, because otherwise the females will use them as a detour to their destination.
In order to ensure the lasting effect of the glue rings, they should be checked daily for leaves that may be stuck there. Because the female winter moths don’t miss this opportunity to overcome the glue ring with the help of this bridge. The glue rings should remain on the tree trunks until January. They are then disposed of in the rubbish bin, because dying females have deposited their entire stock of eggs here. If there is an obviously severe infestation, you should replace the glue rings from time to time.
Make glue rings yourself
Depending on the number of tree trunks that the hobby gardener wants to attach glue rings to, this measure can become quite expensive. Glue rings for combating the winter moth can also be made yourself, with the following recipe having proven itself so far:
- 100 grams of rosin
- 60 grams of olive oil
- 20 g Turpentine
Rosin is a tree resin that is used quite frequently in the restoration trade and is therefore available in specialist shops.
The three ingredients are heated in a pan over a water bath and stirred until they form a thick, spreadable mass. The tree is now wrapped with 10 cm to 15 cm wide strips of wrapping paper, which are wrapped with wire. Alternatively, you can use self-adhesive crepe paper. There must be no loopholes for the frost moths. These strips are now thickly brushed with the adhesive.
biological control
Which hobby gardener likes to use chemicals to get rid of winter moths on his fruit trees? The harvested fruits can then no longer be enjoyed with a clear conscience. Therefore, some effective methods of biological control of these pests are presented below:
Hang nest boxes in the garden
The natural enemies of the winter moth caterpillars include songbirds of all kinds and woodpeckers. For them, the frost moth caterpillars are welcome prey to feed to their offspring. The garden is designed to be inviting for the birds with nesting boxes. They are attached at a height of about 180 cm, with the entrance hole facing south-east and protected from the rain as much as possible.
Bacillus thuringiensis
This natural bacterium is harmless to humans, beneficial organisms and plants, but after a few days it kills the frost moth caterpillars that eat the product. Before that, however, it causes an immediate stop to eating, provided you use it when the temperature has been at least 15° Celsius for at least 3 days in a row.
parasitic wasps
These parasitic insects not only destroy the dreaded codling moth or aphids, they also don’t give winter moths a chance. They are proven to be more effective against the feeding pests than any insecticide. With their long ovipositor they place their eggs in the eggs of the winter moth females. Instead of a voracious frost moth caterpillar, a parasitic wasp larva hatches from this host egg after a few days.
There are now more than 40,000 species of parasitic wasps around the world, many of which have specialized in very specific pests. These beneficial insects can be purchased in garden centers and other specialist shops. Once established, they will multiply naturally in the garden, provided they are given the right conditions to do so. Because they don’t live in colonies, the females lay their eggs in solitary brood tubes, preferably in old fence posts, hollow plant stems, or rotten wood. Anyone who offers them these nesting aids can assume that they will feel at home in the garden and will take care of combating winter moths in the future.
Other natural enemies
Free-ranging chickens discover the pupated cocoons in the ground or prey on them when they crawl to the trees. In addition, caterpillar flies, spiders, carabids, and other beneficial insects devour the eggs and caterpillars of winter moths. These animals find good living conditions in hedges, preferably consisting of native trees and herbs. What is meant, however, is not the accurate “authority hedges”, but the nature-loving Benjes hedges. They are not only significantly cheaper than the precision hedges, but also offer the beneficial insects in the garden onenatural habitat. A Benjes hedge consists of stacked root knots, brushwood, branches and other organic material. Here the animals find shelter and food. Over time, herbs and wild perennials settle, the wood rots and an ideal home is created for all the useful insects in the garden, which put an end to pests such as the winter moth. In the deluxe version of the Benjes hedge, its material is accumulated over a pile of natural stones with small waterholes.
Pheromonfallen
The females ready to mate emit certain scents that attract the male winter moths. A pheromone trap simulates this scent, but consists of a box with glue that the butterflies can no longer escape. In this way you can significantly reduce the reproduction of winter moths. However, this form of control is only advisable if there are a few fruit trees in the private garden and no other trees are being grown in the immediate vicinity. Otherwise, all the Frostmouse moths in the neighborhood will be invited to come to the home garden, which will result in exactly the opposite of control. Alternatively, of course, a pheromone attack planned together with the neighbors can be carried out.
confusion method
This form of biological control of winter moths also uses attractants, but not in conjunction with a trap. The pheromones are sprayed widely between the fruit trees and berry bushes, so that the males are so confused that they can no longer find the females.
Combat winter moths on ornamental plants
As already mentioned, the winter moths not only infest fruit trees and berry bushes, but also attack ornamental plants. Since the effective procedure with glue rings does not work in this case because the stems are simply too tender and weak, clever hobby gardeners have developed some adapted strategies for biological control.
Brunonia glue
This caterpillar glue is a creeping glue, which means it only holds onto the pests that crawl inside. Compared to adhesive glue, this has the advantage that trapped insects do not form a “bridge” for subsequent winter moth caterpillars. Brunonia glue is gentle on beneficial insects and weather-resistant. Insects that are only looking for a place to land are released immediately. The female moths get stuck and cannot lay their eggs.
hard toothbrush
Anyone who observes their ornamental plants with eagle eyes at the time when the females are laying their eggs can quickly recognize the eggs because of their orange colour. A hard toothbrush puts a rigorous end to the infestation of the plant by the winter moth. If you want to get rid of the winter moth very thoroughly using this method, take a magnifying glass and examine the endangered plants again, as the eggs are still whitish in the very early stages.
Conclusion
Experienced hobby gardeners rightly shy away from using chemical clubs to get rid of the dreaded winter moth on fruit trees and berry bushes. Fortunately, there are a number of biological agents and methods that have been proven to successfully combat this plague. Anyone who deals with the life cycle of the winter moth will appreciate the effectiveness of the recommended strategies. One of the most effective utensils is the glue ring, which you can even make yourself. However, promoting the winter moth’s natural opponents will sooner or later achieve the desired success in the fight against this pest.
