The larvae of May beetles are among the most harmful among the so-called grubs. They can cause significant damage to the lawn or to ornamental and useful plants in the garden. However, there are effective ways to recognize them and limit their harmful effects.
How do you control and prevent cockchafer grubs in the garden?
Cockchafer grubs are harmful larvae that eat roots of ornamental and crop plants and can cause lawn damage. To combat them, you should dig up the soil, remove the larvae and use predatory nematodes. Preventative measures include regular mowing, scarifying and careful soil care.
The harmful potential of cockchafer grubs
Of all the grub species that occur in our Central European latitudes, cockchafer larvae are the most feared. During their three to four year underground development phase, they eat thick and round delicate roots of all sorts of ornamental and useful plants. If there is increased volume, this can cause a certain amount of damage, especially in garden lawns and vegetable beds.
Compared to times before 1950, however, the concentration of cockchafers is no longer really threatening. Because the animals regularly caused crop failures and tree defoliation, they were heavily combated and almost eradicated until the second half of the 20th century. Today, the extent of damage, especially in private gardens, is therefore rather moderate.
To remember:
- May beetle larvae are among the most harmful grub species
- The number of cockchafers has declined sharply since the second half of the 20th century
- Damage in private gardens therefore moderate
How do you recognize cockchafer grubs?
Cockchafer grubs have a very grub-typical appearance: with a length of 5-6 centimeters, they are medium-sized and therefore quite easy to find. Their thick, caterpillar-like segmented body is curved in a C-shape. When he collects it, he contracts even more. The body color of cockchafer grubs is yellowish-creamy white, the slightly thickened abdomen is dark and the head is brown. There are 3 long, bent pairs of legs attached to the chest, which serve as digging tools for the grub.
Damage and combating it
Typical indications of a May beetle grub infestation are dry-looking, easily removable islands in the garden lawn and dying ornamental and vegetable plants in the bed. If you dig up the soil under a dead island of grass, you can identify the eaten roots and probably the grubs as well. As a first measure, such digging and manual removal of the pests makes sense.
For targeted and complete control, it is recommended to use predatory nematodes (€29.00 on Amazon) on the larvae. You can order these online, for example. They parasitize the grubs and kill them reliably.
Prevention
In order to avoid getting into trouble with the voracious May beetle grubs, preventive measures also make sense. Above all, thorough, regular soil care is the be-all and end-all here. To make it more difficult for adult cockchafers to lay eggs in the lawn, you should mow and scarify it regularly. This will strengthen the turf.
In beds, it helps to weed diligently and, if necessary, to put insect protection nets over them during the flight times of the adult beetles, i.e. in May and June. Of course, this only applies to the cockchafer years, which are repeated approximately every four years according to the larval development period.
In order to keep adult cockchafers away, you should also avoid night lighting in the garden. They attract the light-orientated beetles and promote their establishment and egg laying.
