How to fight annoying June beetles: tips for your garden!

How to fight annoying June beetles: tips for your garden!

They are flying high again in the gardens of northern Germany: the June beetles (Amphimallon solstitiale) have started their season. Garden owners are alarmed because the small insects can cause significant damage to lawns, plants and trees. These beetles are significantly smaller than the often feared May beetles; their size is between 14 and 18 millimeters. Their caramel-colored, hairy body and yellowish-brown, ribbed wing covers are distinctive and easy to recognize. In comparison, cockchafers reach a length of 25 to 30 millimeters and have red-brown wing coverts and a black head.

However, the June beetle larvae, better known as grubs, are the real culprits. These cream-colored larvae, which are up to three centimeters long and have a brown head, freely eat the roots of living plants, which often leads to dying plant parts and unsightly, yellow lawns. Damage is quickly visible: the upper parts of the plant begin to wilt and the blades of grass can be easily pulled out of the ground. What is particularly problematic is that these grubs mainly occur in sandy soil, while they are harmless in compost or mulch because useful grubs live there and help form humus.

activity and development

The June beetles have a two-year development cycle and are active from mid-June to mid-July. During their nocturnal flights they orientate themselves on dark silhouettes, which gives the impression that they are “attacking” their gardens. The females lay around 40 eggs in sandy, light soil, from which the grubs hatch after around three weeks. These go through three stages of development and overwinter in the ground.

The damage caused by June beetles and their larvae can be significant. Dying plants and burnt brown patches in the lawn that are easily peeled off are common signs of an infestation. While the adult beetles do eat leaves, their short lifespan means that their damage is not as serious as that of the grubs, which can turn out to be a real pest.

Control and prevention

Garden enthusiasts who want to combat these pests have several methods at their disposal. Biological control with nematodes (Heterorhabditis bacteriophora) is an effective option because these parasites penetrate the larvae and kill them using a bacterium. Encouraging natural predators, such as birds and hedgehogs, can also help keep the June beetle population in check. Mechanical methods such as deep tillage or special fungal granules are also available, but should be viewed as a last resort.

As a preventative measure, garden owners should rely on intensive lawn care. Regular mowing, fertilizing and loosening the soil are crucial here. Lawn protection fabrics also help protect the soil in heavily affected areas. It is important to choose the right time for control because nematodes are optimally used when the grubs are in the first stage of development, i.e. in August and September.

In summary, June beetles are an annoying but not dangerous phenomenon in our gardens. If you have a good knack for caring for your plants and follow a few simple tricks, you can keep both June beetles and their larvae well at bay. Further information on identifying and combating pests can be found at az-online, Plants School and Legona.