Grubs (Cockchafer) - Natural enemies & measures

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Grubs (Cockchafer) - Natural enemies & measures: beetles

Every 40 years there is a huge plague, as the May beetles occur in large numbers and cause devastating damage. The feeding of the grubs causes far more damage. Although they eat first dead plant parts and hair roots. By root damage, however, they can damage whole trees so far that a gust of wind brings them down. Most at risk are young trees, especially deciduous trees. The infestation is noticeable by small growth. Then the tops are slowly dying off.

Enemies of the cockchafer and measures

  • owls,

    Bats, birds of prey, crows and sparrows are natural enemies of the beetles. The Engerling has many more enemies, blackbird, green woodpecker, hedgehog, ground beetle, mole, gulls, parasitic nematodes, caterpillar fly, shrew and star. But also in the soil bacteria, nematodes. Mushrooms and viruses endanger them.
  • The pests do not like garlic smell and also no frequent tillage. If you aerate the soil well, eggs and young larvae are killed. Beetle can be shaken from the tree and collected. Beds are covered with fleece or vegetable fly nets in the time of flight of the beetles. Grubs love dandelion roots. When they find enough, they leave everything else alone.

  • Engerlings can be caught well in a horse trap. Mix a bucket of horse manure with compost and bury it about 50 cm deep in the ground. It is best to take several buckets. In the spring you can dig out the buckets and kill the grubs gathered there. If one expects the invasion of the beetles, which occurs every four years, one should mow his lawn only when the May beetles have laid their eggs. The eggs dry up in the grasses.

  • In the near future, a fungus may control the stocks of cockchafers. At the moment, tests are in progress. Cockchafs multiply in the Rhein-Main-Plain. Particularly affected are deciduous trees. Many acres of forest forests show severe damage. Access to the grubs is difficult as they spend more than three years underground. Now you try to lure the forest cockchafer in traps and infect them there with the mushrooms. When mating, the fungus is passed on to the partner and thus indirectly to the larvae. The next spring will show how the fungal spores have spread

  • Previously solved the cockchafer problem differently. Especially in the years when there was not enough food for all, the beetles were eaten. In confectioneries, the beetles had even saccharified. Candied maybugs for dessert were considered a delicacy.

useful information

"There are no more Maybugs", sang Reinhard Mey many years ago. What comes nicely packaged as lyrics, however, has a serious background. Thus, the May beetle stock has declined sharply in the past decades.
  • The cockchafer, which largely feeds on leaf leaves - which incidentally was also the reason for its massive fight -, digs out about April to May from the

    Ground and then flies around until about June.
  • The life of the beetle is usually one month to about 7 weeks. All species have the common for the beetle typical (fan-like) feelers, which are incidentally less pronounced in females than males.

  • The cycle time of cockchafers is about 4 years, with the result that 3 years with low weevil occurrence is followed by a year in which there are many cockchafers. However, due to the sharp decline in the May beetle, in most regions there is little talk of cockchafer plague that has been described many times in the past

The best known species of the cockchafer beetles are the beetle

  • the field cockchafer, Melolontha melolontha, which occurs mainly in Central Europe
  • the Feldmaikäfer similar Melolontha pectoralis, which is occasionally still to be found in Central Europe and
  • the woodland beetle, Melolontha hippocastani, which mostly occurs in Northern and Eastern Europe as well as in decimated numbers also in Germany

Reasons for the decline of the cockchafer population

  • Especially in the 50s and 60s, the cockchafer was massively fought with the now forbidden insecticide DDT.
  • Parasite infestation is also thought to be the cause of the beetle decline, with one likely to generally result in years of low annual beetle emergence followed by cycles of cockchafer plagues
  • The increased nitrogen over-fertilization of agricultural soils has also been cited as a reason for the dying of cockchafer

Are the cockchafers back?

Despite the strong decline of the May beetles in the past reports of cockchafer pests, which are said to have led to forest dying, reached the public. South Hessen, where hundreds of hectares of forest were treated in 2010 with an insecticide that acts against cockchafer, was in the focus of public attention. In particular, nature conservation organizations criticize this approach, but it is rather assumed that the cockchafer be a symptom, not the cause of the forest dying in southern Hesse.

Video Board: Cockchafers - Melolontha melolontha - Aldinbori - Ýflaætt - Bjöllur.

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