The larvae of the rose sawfly (Caliora aethiops) feed on the upper side of the leaf and cause unsightly damage. These dry out after a while and leave holes. Affected leaves should be removed and disposed of with household waste, never in the compost. There the larvae develop further, so that an infestation is promoted in the next year.
Pesticides should always be the last resort - they cause serious harm to the environment, humans and animals
biology and damage
The greenish larvae, about ten millimeters long - the real pests on the rose petals - can be seen with the naked eye, quite differently from the adult black animals, which are only about five millimeters long. These fly from April, or earlier if the weather is good, and lay their eggs on the top and bottom of the roses. From May and June you can finally recognize an infestation by the scraping damage spots, especially on the edges and tops of the leaves. Real holes appear in the leaf, with the rose slowing down or even stopping growth in the event of a severe infestation. In autumn, the larvae burrow into the ground around the rose and pupate there during the cold season, only to infest the rose again as adults the following spring.
Combat rose sawfly naturally
The rose sawfly can be combated very well in a natural way, with the following measures in particular having proven to be effective:
- Promote the settlement of beneficial insects (e.g. parasitic wasps), birds and hedgehogs in the garden.
- Set up insect hotels, piles of sticks and leaves in corners of the garden.
- Feed the songbirds in winter, but stop feeding when the leaves sprout.
- Collect the larvae.
- Remove affected leaves and shoots.
- Only dispose of the clippings with household waste,
- this should help to avoid reinfection.
- Collect fallen leaves and dispose of them with household waste.
- In late winter, till the soil to disrupt pupation.
- Spray the roses with horsetail tea to prevent and strengthen them.
- If an infestation has already taken place, a cure with oak manure helps.
Make oak manure
Collect about a kilogram of oak leaves and pieces of bark to ferment in water (preferably collected rainwater) for 14 days. The liquid manure should be covered and stirred daily. After 14 days, dilute the brew 1:10 with water and apply it to your affected roses.
Only use pesticides if the infestation is very severe
Pesticides not only kill rose sawflies and other pests, they also kill beneficial insects. However, these are important to prevent further infestation. Therefore, avoid using environmentally harmful agents as far as possible, after all, with a little effort, this parasite can also be combated with household remedies.
tips
If the rose petals curl up, there is probably an infestation with the rose leaf scroll wasp.