It is not uncommon for the euonymus to be covered in fine webs in the spring. The reason for this is the spindle moth. The moth has specialized in the wood and uses it every year to lay eggs.
Spinning caterpillars on the euonymus are the larvae of the spider moth
Look
The caterpillars of the spindle moth are light brown in color and dotted with black. The yellow-brown head is clearly separated from the body. The moths are very small with a wingspan between 18 and 24 millimeters. Her head and appendages are colored white. Typical are the white-grey wings, which are dotted with black. Their hind wings are gray to brown in color.
way of life
The moth flies between July and August. They often do not move more than 100 meters away from their hiding place. Females emit scents that attract males. After successful fertilization, the females lay eggs in clutches of 50 to 100 on the branches of the spindle tree. The larvae burrow into the branches and hibernate there.
In May they eat tunnels in the terminal leaves, which slowly wither. Between May and June there can be a mass appearance of the caterpillars, as they live sociable in webs. The fine cobwebs can cover the entire shrub. The caterpillars stop eating four to five days before pupation. They pupate between June and July in a white web containing numerous cocoons. After ten to 20 days, the new moth generation hatches.
damage
When a euonymus has become completely encased in the webs, it can be eaten completely bare. By the second shoot, which takes place around June 24th, the caterpillars have stopped eating and pupated. This allows the spindle tree to recover well from pest infestation.
prevention
If your shrub has already been infested by the spider moth, it is likely to be infested again. Before winter, scrape the eggs from the branches. Observe the plant in spring and remove mined leaves. These should be disposed of with the residual waste so that the caterpillars do not spread further. Remove webs as early as possible by spraying the entire bush with a powerful jet of water.