May beetles and June beetles are among the best-known flying insects that like to stay in German gardens from May to July. Children love to catch them, cats chase them, and gardeners and farmers despair when their plants are used as food by the beetles because they are extremely hungry. If they become a summer nuisance, it is important to combat them. But how dangerous are they and do they harm people and animals?

Danger

All clear: harmless to humans and animals

You don't have to worry if you pick up June beetles or may beetles or if your cat eats one of the beetles. They are not poisonous, stinging or blood-sucking. For house cats, they even represent a snack that they hunt under their own steam, which is good for the cat's instincts. Although the feet, which are equipped with claws, can hold on, which hurts a little, May beetles and June beetles are not dangerous to humans or animals. However, the adults and grubs, the larvae of beetles, can be dangerous to your garden plants and lawn due to their large appetites.

Tip: many people are afraid of June beetles when they fly towards them quickly. However, this is not an attack on the part of the beetle, but the staggering way of flight, since they are not as good at flying as other insects.

cockchafer

How dangerous are adult animals?

June beetles and may beetles can quickly become a nuisance due to their eating habits, but this can still be contained. The two beetles differ in terms of preferred plant parts and the season in which they forage to prepare for reproduction. The differences follow in detail.

cockchafer

Melolontha species feed primarily on the leaves of numerous tree species. They prefer free-standing deciduous trees and shrubs, which they eat together in larger groups completely bare within a few weeks. They only feed on the leaves in May, which gives the trees enough time in the summer to let them grow back. Because of this, cockchafers in themselves do not pose a threat to the plants, as the plants can easily recover.

June beetle

The June beetle, on the other hand, can become a nuisance from July, as it eats the blossoms and leaves of typical garden plants well into the autumn. It is less interested in trees, but will even eat rose bushes or other ornamental plants. The plants can suffer massive losses of plant material and some lose their actual winter protection. That's why many gardeners want to get rid of the bugs. They also like to snack on the lawn, which can lead to an unsightly lawn.

June beetle

Although the adult beetles use the plant material, they do not count as pests. It does happen every year that a particularly large population develops, which of course means that more leaves and flowers are eaten. However, it only becomes really problematic when there are many beetle larvae in the soil, which can grow into a harmful plague.

grubs

Why are grubs dangerous?

The larvae of May and June beetles are known as grubs, which remain in the ground for years after hatching.

Depending on the beetle species, the duration of this period varies:

  • cockchafer: 3 - 5 years, mostly 4 years
  • June beetle: 2 - 3 years maximum

During this time, the larvae feed on underground plant materials, mainly roots, but also bulbs and tubers, anything they can get between their mouthparts. And this is where the problem lies. Many larvae feed on roots, but grubs do this for years, and each year they get bigger and eat more. This can seriously endanger the health of the plants, especially if they are sensitive plants. It doesn't matter whether you have May beetles or June beetles in the garden, the young animals can feed for a long time until they pupate and then go looking for a partner.

beetle larvae

combat

Control June beetle and May beetle larvae

If you want to get rid of the animals, you must first look out for a few symptoms. Since the larvae feed primarily on the roots, the plants visibly suffer as the supply of nutrients and water is cut off.

Typical symptoms of an infestation are:

  • weak and young trees die
  • Rose bushes die
  • Lawns present dry and yellow patches
  • Lawns dry up and eventually die

The symptoms are particularly noticeable with good care of the plants. Even if you take great care of your lawn and it dies, it could be because of grubs. If you notice that there are many June and May beetles in your garden over the spring and summer, your suspicion will be increased. In order to get rid of them, good prevention is necessary.

grubs in the ground

This is implemented as follows to combat the grubs:

  • allow large areas of the garden to dry out
  • the beetle larvae need moist soil and die as soon as it is too dry or the UV radiation is too high
  • only water individual plants that need a lot of water
  • the females will now look elsewhere for places to lay their eggs
  • dig up the soil with a cultivator, the material of which contains zinc;
  • this works against the beetle larvae

You can also prevent the larvae from settling if you bring natural predators into your garden.

This includes:

  • moles
  • birds of all kinds
  • shrews
  • cats
  • bats

These animals thrive on cockchafer grubs and June bugs, as they provide plenty of energy and nutrients. If the beetle plague is already in full swing, you have to fight it in a targeted manner. There are a variety of means and methods that do not harm the garden and can always be used.

Molehills in the garden

scent traps

Scent traps are great for catching the adult males so they don't get to the females to fertilize them. These lure the males into the trap via pheromones, from which it is no longer possible to escape from the inside. So the male is stuck and can't get out of the trap. These traps are easy to set up and available from specialist retailers. Depending on the manufacturer, the costs for the scent traps vary between 20 and 50 euros.

milling

Simply till the garden regularly from late May to early August. The milling machine ensures that the ground is dug up, exposing the beetle larvae. These are now unprotected from the sun and exposed to predators. Often many of the young animals die during the milling and many of the others are subsequently eaten by other animals or perish in the warm sun. If you don't have a milling machine, you can rent one in hardware stores for about 65 euros per day.

Parasitic fungi (Beauveria brongniartii)

Using Beauveria brongniartii is a good way to control May beetles and June beetles. These are simply placed in the ground and from then on they take care of the annoying pests themselves. These are spread directly onto the lawn or the surface of the earth in summer. The fungi will now start to spread into the soil and kill the beetle larvae from within after they have established themselves in the grubs. Best of all, the mushrooms have a long-term effect of up to 15 years. Costs are around 50 euros for two kilograms.

nematodes

They are the last weapon in the fight against cockchafers and June bugs, which are dangerous in the garden. Nematodes are filamentous fungi that are spread over water. Here they attack the grubs and start killing them from the inside out. This happens particularly quickly and effectively with roundworms. The costs for this are calculated at around 1.1 euros per m² of lawn area.

Tip: please do not use chemical insect repellents to get rid of the beetle larvae. These negatively affect the soil in your garden and can affect your health, especially if you grow vegetables or fruit.