Help: are cockchafer + June beetle dangerous? What to do against larvae

Cockchafer and June beetle are among the best-known flying insects that like to stay in German gardens from May to July. Children like to catch them, cats hunt them and gardeners and farmers despair when their plants are used as a food source by the beetles, as they are extremely hungry. If they become a summer plague, 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 cockchafer 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 on their own, which is good for the house tiger's instinct. Although the feet, which are equipped with claws, can hold on, which is a little painful, May and June beetles are not dangerous for humans and animals. The adults and the grubs, the larvae of the beetles, however, can be dangerous for your garden plants and your lawn due to their great appetite.

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

How dangerous are adult animals?

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

Cockchafer

Melolontha species mainly feed on the leaves of numerous tree species. They prefer free-standing deciduous trees and shrubs, which they can eat completely bare within a few weeks in larger groups. They only feed on the leaves in May, which gives the trees enough time in summer to let them grow back. For this reason, cockchafer per se do not pose a threat to the plants, as the plants can recover without any problems.

June beetle

The June beetle, on the other hand, can become a nuisance from July, as it eats flowers and leaves of typical garden plants until autumn. He is less interested in trees, and instead even eats rose bushes or other ornamental plants. The plants can suffer massive losses of plant material and some lose their actual winter protection. That is 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.

Although the adult beetles use the plant material, they do not count as pests. Every year it happens that a particularly large population emerges, which of course leads to more leaves and flowers being 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 the May and June beetles are called grubs, which remain in the ground for years after hatching.

Depending on the type of beetle, the duration of this period is different:

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

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

Combat

Fight June and cockchafer larvae

If you want to get rid of the animals, you have to look out for some symptoms first. Since the larvae mainly feed 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 spots
• Lawns dry up and eventually die

The symptoms are especially noticeable with good care of the plants. Even if you take ideal care of your lawn and it dies anyway, it may be because of the grubs. If you notice over the spring and summer that there are many June and cockchafer bugs in your garden, the suspicion is even heightened. In order to get rid of them, good prevention is most important.

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 for brood placement elsewhere
• dig up the soil with a cultivator, the material of which contains zinc;
• this works against the beetle larvae

You can also prevent larvae from settling by bringing natural predators into your garden.

This includes:

• moles
• Birds of all kinds
• Shrews
• Cats
• Bats

These animals feed wonderfully on the grubs of the cockchafer and juniper beetle, as these offer a lot of energy and nutrients. If the beetle plague is already well underway, you have to fight it specifically. There are a variety of means and methods that do not harm the garden and can always be used.

Scent traps

Scent traps are ideal for capturing adult males so that they can no longer reach the females to fertilize them. These lure the males into the trap using pheromones, which can no longer escape from the inside. So the male is stuck and can no longer get out of the trap. These traps are easy to set up and are available from specialist retailers. Depending on the manufacturer, the cost of the fragrance traps varies 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, which exposes the beetle larvae. These are now exposed to the sun and predators without protection. Often many of the young die while milling and many of the others are then eaten by other animals or perish in the warm sun. If you don't have a tiller, you can borrow it in hardware stores for around 65 euros per day.

Parasitic mushrooms (Beauveria brongniartii)

Using Beauveria brongniartii is a good way to control cockchafer and junior beetle. These are simply put in the ground and from then on take care of the annoying pests themselves. In summer, these are distributed directly onto the lawn or the surface of the earth. The mushrooms now begin to spread into the soil and kill the beetle larvae from the inside out after they have established themselves in the grubs. The best: the mushrooms have a long-term effect of up to 15 years. The cost is around 50 euros for two kilograms.

Nematodes

They are the last weapon in the fight against cockchafer and juniper beetle, which are dangerous in the garden. Nematodes are filamentous fungi that are distributed over water. Here they attack the grubs and begin to kill them from within. This happens particularly quickly and effectively with the roundworms. The costs for this are calculated at around 1.1 euros per m² of lawn area.

Tip: please do not use chemical insect repellants 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 fruits.