The larvae of the spider moth can eat entire trees bare and reduce the fruit harvest. In the event of an infestation, quick action is required.
Observant walkers will often find bizarre-looking trees and shrubs in parks and gardens. Even in your own garden it can happen that the plants are surrounded by a silvery web.
It's very likely that the Web Moth was at work. However, the nests can also be confused with those of the oak processionary moth. In the following we will tell you how to recognize the spider moth, which plants are particularly affected and what can be done about it.
Which plants are affected?
Very different plants can be covered by the cloud-like nets.
Particularly endangered are:
- Poplars
- Willows
- Hawthorn
- Cherries
- Spindle Hat
It is not uncommon for fruit trees to be affected. A distinction is made between the apple tree spider moth and the plum tree spider moth. The moths mostly infest apple, plum and plum trees. The webs also appear less frequently on peaches, apricots or pears. With a heavy infestation, entire treetops can appear spun.
While the infestation of the other plants appears relatively harmless, the spider moth poses a real threat to the fruit harvest.
Recognize Spider Moth
The moths are about one centimeter long. Characteristic are the white-grey wings, on which black dots settle. The gray hind wings appear like a pointed roof when closed. The wingspan of a spider moth is about 2.5 centimetres.
The larvae are dark green to brownish in colour. The bodies are divided into ten segments. A black dot appears on each side. The caterpillar head is also colored black. When the caterpillar is illuminated by light, the innards stand out clearly from the transparent body in the form of a brown line. Occasionally delicate hairs can be seen on the body.
Coast moth or oak processionary moth?
It may be the comparatively harmless spider moth or the dreaded oak processionary motheveryone check themselves. While the caterpillars of the spider moth hardly have any hair, the caterpillars of the oak processionary moth have fine stinging hairs.
These hairs are particularly insidious and can lead to he alth problems, even if the pest is not touched. The hairs break off and fall from the trees and bushes. They can trickle down on us and trigger allergic reactions. Itching or hives may occur. In extreme cases, there is a risk of anaphylactic shock.
Warning: If it is the oak processionary moth, do not touch the nests and contact pest controllers.
The caterpillars of the spider moth, on the other hand, are completely harmless to humans and can only do little harm to plants.
Life Cycle of the Spider Moth
A generation of spider moths grows up each year. If nothing is done about them, they can multiply undisturbed in the home garden for up to ten years.
The moths lay their eggs on twigs and shoots. The oviposition is provided with a protective secretion and is thus sufficiently protected. The caterpillars hatch a few weeks later and hibernate under this protective cover. In the spring they appear on the leaves and eat in the webs that have been laid out. It is not uncommon for them to become bare.
Pupation of the caterpillars usually takes place at the beginning of June. Then the danger for the plants is averted. After two more weeks the moths fly out. They mate and start laying eggs. This starts the life cycle of the spider moth all over again.
How bad is the damage?
If the plants are heavily infested, it is not uncommon for the entire plant to be covered with a dense web and eaten completely bare. However, when the caterpillars pupate, the plants usually recover surprisingly quickly and sprout again around June 24th. This is called the Johannistrieb. Trees and bushes are not permanently damaged by the infestation with spider moths. Harvest losses must be expected in fruit crops alone.
Fight Spider Moth
Since trees and shrubs are not badly damaged, controlling moths in ornamental gardens is not absolutely necessary. On the other hand, targeted control is advisable if fruit trees are heavily infested.
However, the infestation is usually only noticed when the webs have already been created. Then combating it with pesticides becomes difficult. The funds roll off the webs and theActive ingredients cannot penetrate to the caterpillars inside.
If the infestation was noticed before the webs were created, bee-friendly neem-based preparations, such as organic pest-free neem from nature, or other active ingredients can stop the infestation. Furthermore, natural predators can be used with parasitic wasps and assassin bugs.
If the webs are treated with a hard jet of water, they are usually destroyed. Furthermore, the nests of the caterpillars can be cut out of the plants and disposed of.
Tip: To prevent this, the eggs can be scratched off the trees and bushes in winter.
Prevent spider moth
Glue rings are helpful to prevent an infestation in the first place. These are already attached to the trunks of the plants in September. However, this only makes sense if there are no larvae in the tree yet.
Another preventive measure are pheromone traps, which contain attractants. So the spider moths can't multiply as much.