When entire bushes are covered in white webs in early summer, many people suspect a devastating pest infestation. At least the spider moths that settle on the spindle tree are not dangerous. Anyone who is bothered by the webs can prevent them or fight them directly.
The larvae of the spider moth can eat entire branches bare, but the bush will recover from the deforestation
Look
The spindle moth develops a wingspan of between 18 and 24 millimeters. The small moth is easily recognizable by its light gray to white wings, which are dotted with black. The underwings appear brownish. When the moth is at rest, its wings are closed in a steep canopy.
The moths fly between July and August. Their eggs are rounded to flattened and initially yellow in color. They are coated with a sticky secretion that hardens and turns brown over time. The bodies of the larvae are light brown to dark green in color and dotted with black. Their head appears yellowish to brown.
way of life
The spider moths lay about 50 to 100 eggs on the branches of the spindle tree. They overwinter and hatch next spring when the weather is warm and dry. The caterpillars burrow burrows into the leaves, which wither and die over time. Between May and June, the caterpillars live in fine webs that can sometimes cover entire trees. In the case of a severe infestation, the shrub can be eaten completely bare.
The spider moths stop eating about four to five days before pupation, which takes place from June to July. The caterpillars form a dense collection web in which the cocoons hang down vertically. After ten to 20 days, the next generation of nocturnal moths hatch.
prevention and control
Normally, control is not necessary as spindle trees survive the infestation well. As a preventive measure, you can scrape the eggs off the affected branches in winter. If you find pierced leaves during the spring, you can cut them off and dispose of them with the general waste. Remove webs, including caterpillars and cocoons, by spraying the bush with a powerful jet of water.
If you encourage natural enemies of the spider moths, you ensure a natural balance. Ichneumon wasps (€22.99) and assassin bugs keep the moth populations in check. They ensure that the voracious caterpillars cannot spread unrestrictedly. The beneficial insects feel comfortable in gardens that are designed to be close to nature.
Where parasitic wasps feel comfortable:
- in tufts of grass and tree stumps
- under loose tree bark and moss
- in flowers of umbelliferae
No danger
It looks as if the spider moths have a firm grip on the bush and are going to kill it. As a result, they are feared by many garden owners, but the spindle hats are not harmed. Spindle hats are not damaged, however, because otherwise the spider moths would destroy their own livelihood. The bushes sprout again around June 24, the so-called Johannistrieb.