Careful garden leaf beetle control is particularly advisable from July to September, when the females burrow into the lawn to lay their eggs. If you do not act, the unsightly brown spots in the lawn can spread, because the garden leaf beetle larvae feed on the grass roots.
Have you already noticed brown spots on your lawn? Do you have garden leaf beetles? Then you should take action. Read how to recognise the damage and what successful garden leaf beetle control can look like.
Garden leaf beetle control – recognising the damage
The small, yellow spots on the fresh green lawn are noticeable. The grasses have died here because someone has eaten away the roots. And this someone – there are often quite a few of them – are the grubs of the garden leaf beetle (Phyllopertha horticola). If you lift the sod, you can see them lying underneath. The beetles hatch at the end of May or beginning of June and feed on the foliage of shrubs and trees. They like to be out and about in the midday and afternoon hours, unlike the similar-looking May beetles which tend to fly at dusk. After mating in June, the females burrow into the lawn to lay their eggs. They prefer loose, light soil or bare patches in the lawn. Depending on the weather, the larvae hatch about four weeks later and begin to feed on the grass roots. To control garden chafer, this cycle should be broken.
Control of the larvae
Beneficial insects have proven successful in controlling garden leaf beetles. Nematodes of the species Heterorhabditis bacteriophora are helpful against the garden leaf beetle larvae. As soon as the first damage appears in the lawn, you can treat the spots with them. The microscopic nematodes penetrate the larvae and kill them within a few days. The best time to apply the nematodes for successful garden beetle control is from July to September. In order for the nematodes to spread well in the soil and swim to the grubs, the lawn should be well watered before and after treatment.
Crows and other birds, moles and wild boars are happy about the grubs, but can completely destroy the lawn in their search.
Control of the beetles
Controlling garden leaf beetles is somewhat more difficult. They can be caught with attractant traps after hatching from the end of May. However, this is more to detect an increased occurrence of the beetles in order to then control the larvae later in the summer – and thus break the cycle.