The cockchafer is the symbol of the dramatic change in nature. Formerly a plague fought vehemently with tons of poison, a mass occurrence is now considered a well-noticed sensation with great media hype. We present the humming heralds of spring with great appetite.

Cockchafers were about to leave our planet forever

Table of Contents

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  1. the essentials in brief
  2. Portrait of a may beetle
  3. Cockchafer larva life path
  4. May beetle June beetle difference
  5. May beetles under nature protection?
  6. Fighting cockchafers makes sense?
  7. frequently asked Questions

    8. the essentials in brief

    • May beetles hum loudly, are 2-3 cm long, have red-brown wings and conspicuous antennae with 6-7 lamellae.
    • Cockchafers crawl out of the ground in spring, prefer to eat tree leaves and have a short lifespan of 4-7 weeks.
    • A cockchafer larva is cream-colored, has 6 legs, becomes as thick as a finger, lives in the soil for 3-4 years and feeds on plant roots.

    A portrait of a cockchafer - profile and way of life

    When big buzzers buzz through the air on mild May evenings, it's cockchafer season. The clumsy flight is due to the shape of the body, but at the same time symbolizes the heavy burden of prejudices that cockchafers carry around with them today. Extensive mass proliferation with defoliation on treetops branded may beetles as a dreaded plague until the middle of the 20th century. Today, mass flight years are a rarity and limited to local occurrences. Most children, adolescents and young adults have never seen a cockchafer live and in color. The following table summarizes important characteristics of standing and lifestyle:

    features
    size 20-30mm
    Color elytra reddish brown
    Rear wing membranous, transparent
    color body black with white hairs
    anatomy oval, pointed abdomen
    body drawing white jagged flanks
    sensor 6- to 7-lobed antennal compartments
    insect family Scarab Beetle (Scarabaeidae)
    Most common type Cockchafer (Melolontha melolontha)
    common type Cockchafer (Melolontha hippocastani)
    May beetle food Deciduous forest and fruit trees
    Lifespan imagines 4 to 7 weeks
    larva cream, brown head
    Food cockchafer larva roots, tubers
    lifespan larva 3 to 4 years

    Field and forest cockchafers largely agree in appearance and lifestyle. Differentiating between the two species is a challenge even for the experienced specialist. For this reason, the two conspecifics are considered together here under the term cockchafer. The following important questions and answers provide more detailed information on the above fact check:

    What does a may beetle look like?

    The jagged white flanks are a typical feature of the cockchafer

    Cockchafers have a round-oval body shape that tapers at the back and is two to three centimeters long. Elytra, legs and antennae are reddish brown. The head, chest and abdomen are black in color with thin whitish hairs. A jagged, white marking on the flanks of the abdomen is conspicuous. The abdomen itself is not covered with wings. Four longitudinal ribs can be seen on each red-brown elytra. The hallmark of a may beetle is its distinctive antennae with a fan-shaped club at the upper end. Cockchafer males have a fan made of seven lamellae. There are only six of the Beetle ladies. The antennal compartments of a male are almost twice as long as those of a female.

    What do cockchafers eat?

    Adult cockchafers are veritable eating machines. Leaves from deciduous trees, preferably oak and beech, are on the menu. The foliage of fruit trees is also not scorned. In gardens and parks, the voracious beetles like to devote themselves to the leaves of maple trees. When all the leaves have been eaten, cockchafers are forced to fly to coniferous trees to continue eating there. It is good to know that the affected trees can easily cope with this defoliation. At the latest with the St. John's shoot at the end of June, the trees compensate for the loss of leaves.

    How long do cockchafers live?

    Cockchafers spend most of their lives as larvae

    Adult cockchafers only live a short life of 4 to 7 weeks. When they crawl out of the ground as mature adults, cockchafers have already spent 3 to 4 years of their lives as larvae. As soon as the doll's cradle has slipped out of the ground, two important tasks are on the schedule: eating and multiplying. A prodigal maturing feast precedes mating. Male cockchafers die immediately after mating. Female cockchafers live a little longer to lay eggs.

    Where can you find cockchafers?

    Cockchafers prefer to stay close to their food sources. Larger populations are mainly found where the soil is loose, sandy and good for digging. Thus, the habitat extends over the following areas:

    • deciduous and coniferous forests
    • Heath areas in the north and east
    • Forest areas on the Upper Rhine
    • orchards and orchards

    May beetles cannot be found in swampy and dry or rocky landscapes.

    What does cockchafer year mean?

    In cycles of three to four years, there is a cockchafer year. At this time interval, the beetles appear in large swarms and bare trees. The reason for this are natural population fluctuations as an ingenious survival strategy. The development of the larvae in the form of grubs takes between three and four years. As if the cockchafers had agreed, armies of adult beetles start their maiden flight synchronously in May.

    Researchers suspect that this is how cockchafers trick their predators, because birds or bats can never be sure how many beetles are available as a food source in a year. A main flight year is followed by two to three years with minimal beetle populations in fields and forests. This cycle is superimposed by a mass emergence every 30 to 50 years when millions of cockchafers develop into a plague above and below ground.

    Is the cockchafer a pest?

    Cockchafer grubs cause great damage to roots

    This question has always been a controversial topic in Germany. Conservationists and beetle lovers revere cockchafers as lovable harbingers of spring. Forest owners, farmers and gardeners regard the big bugs and their voracious larvae as pests. The maturing feeding of hatched beetles on tender spring leaves slows down the growth of the trees. The damage caused by grubs in the soil is more fatal. Especially in May beetle years and when there are masses, insatiable larvae damage tree roots so massively that entire stands of young trees die off.

    However, today's may beetle years are nowhere near the dimensions of the past, when all of Germany suffered from a plague with serious harvest losses. The May beetle plague of 1911 is legendary, when a whopping 22 million May beetles were collected on an area of 1800 hectares. Today there are larger occurrences with plague potential at local hotspots, between which there are huge, almost May beetle-free areas. Pest control measures are therefore increasingly viewed critically.

    Life cycle of a cockchafer larva

    While Mr. and Mrs. Cockchafer are popular with the population, the big larvae have a hard time. The grubs are accused of non-stop root damage underground for a period of up to four years. During this time, the larvae go through a total of three instars and complete two to three hibernations. We accompany the development of a may beetle larva from the mating of its beetle parents to the magical moment when it says “may beetle fly” again:

    Oviposition and first year

    After mating, the female cockchafer digs 15 to 25 centimeters deep into the ground. Eggs are laid in one or two clutches, each with around 20 whitish eggs measuring 2 to 3 millimeters in size. A larva hatches from each egg within 4 to 6 weeks. The young caterpillar immediately sets out in search of tasty plant roots. The first moult takes place in late autumn and thus the entry into the second larval stage. Before the onset of winter, the fed grub digs deeper into the ground to escape the frost. The feeding activity will be stopped by next spring.

    second year

    In spring, when the ground temperature exceeds 7 degrees, the May beetle larva perk up. Until late summer, the grub dedicates itself to a non-stop intake of food. The caterpillar is constantly getting longer and thicker. Another moult occurs in September. Now the third larval stage begins with the greatest feeding damage to plants. Only with the onset of winter does peace return until the next season.

    Third and fourth year

    After the second hibernation, the fat larva pupates, which now weighs up to 4 grams live. By autumn, the metamorphosis is complete and the finished beetle hatches. However, the cockchafer does not leave its cradle until May of the following year. As the adult beetles crawl out of the ground, the countdown to maturing feeding, mating, and egg laying begins.

    In colder regions, such as northern Germany or the Alps, the development from a larva to a beetle takes four years. In this case, too, a may beetle hibernates in its pupa cradle in a frost-free depth until it digs itself out of the ground in May for its maiden flight.

    digression

    Record-breaking cockchafer year 2022

    In 2022, the Upper Rhine made headlines as a cockchafer hotspot. After a few quiet years, a may beetle year was to be expected from a purely mathematical point of view. Counts of grubs in the soil in early 2022 confirmed that a mass emergence was imminent in Rhineland-Palatinate. The natural spectacle astounded experts and residents. Up to 100 million cockchafers came out of the ground and populated an approximately 120 square kilometer forest area near Karlsruhe.

    In the following video, beetle experts have their say with detailed information on the memorable May beetle year 2022 on the Upper Rhine.

    youtube

    May beetle June beetle - what is the difference?

    Not every brown beetle that you encounter in spring is called May beetle. A distant relative of the scarab beetle family looks confusingly like a may beetle and is called the June beetle. Both beetle genera share similar lifestyles, with a pronounced fondness for plant foliage, which doesn't sit well with home gardeners. On closer inspection, striking differences can be seen between the June beetle and the May beetle. The following table provides an overview:

    difference cockchafer June beetle
    size 22-35mm 14-18mm
    color reddish brown and black dark yellow to light brown
    hairiness white, spotted, close fitting brown, covering, bristly
    special feature white sawtooth pattern on side ribbed elytra
    sensor 6 to 7-part antennae compartments 3-part feeler compartments
    peak flight time May June July
    activity diurnal nocturnal
    scientific name Melolontha Amphimallon solstitiale
    German name Field cockchafer, forest cockchafer Ribbed tawny beetle, June beetle

    June beetles are significantly smaller than May beetles. A look at the elytra clears any doubts. The June beetle has three raised, yellowish-brown ribs on each elytra, which identify it as a ribbed curlew beetle. Furthermore, the flanks lack the white zigzag pattern that cockchafers decorate themselves with. Although both beetles prefer to swarm out at dusk, cockchafers prefer to eat the dreaded leaves during the day. June beetles, on the other hand, hide during the day and feed under cover of darkness.

    tips

    If you find a fat grub in the compost, it is not a cockchafer larva. Rather, you will enjoy the privilege of encountering an offspring of the very rare and protected rhinoceros beetle.

    Are cockchafers under nature protection?

    Cockchafers are no longer threatened with extinction

    Cockchafers are currently not threatened with extinction. For this reason, the beetles are not listed on the Red List of Endangered Animals in Germany and are not subject to nature conservation.

    Things looked very different in the mid-1970s. In the 1950s and 1960s, tons of highly toxic DDT were vehemently combated. Then a massive may beetle die-off began. With his famous ballad "There are no May bugs anymore" in 1974, the songwriter Reinhard Mey sadly began the swan song of the big bangers. The musical wake-up call was well received by the public. The former May beetle plague became a symbol of nature poisoned and destroyed by human hands. When the Biological Federal Institute in Kiel called on citizens to catch cockchafers in the same year, only a handful of bugs were delivered - despite a bounty of a whopping five Deutschmarks per specimen.

    A lot has happened in favor of the may beetle since then. Gradually, DDT and other toxins were banned nationwide. The result was not long in coming. As early as the mid-1980s, the cockchafer population recovered, at least in some regions of Germany. In most of the country, the likeable Brummer are still very rare to find. Beetle experts and conservationists therefore see the cockchafer in an important flagship function, as a winged representative for countless insect species that are threatened with extinction and urgently need protection.

    background

    Turkish cockchafer is protected

    A giant of the cockchafer family (Melolonthinae) is the Turkish cockchafer (Polyphylla fullo). The gem is up to 36 millimeters long. Its dark brown body is decorated with a white spot pattern. Pine needles are primarily on the menu, which does not result in any economic damage. Unfortunately, the gem from Mother Nature's jewelry box is very rare. For this reason, this extraordinary cockchafer is listed on the Red List as an endangered species and is under nature protection.

    Fighting cockchafers - useful or the day before yesterday?

    There is an increasing rethinking of the fight against cockchafers. Even in problem areas with cyclical mass occurrences, foresters and farmers no longer use toxic insecticides, and with good reason. Fighting with lethal injections from a helicopter is only effective during flight. Widespread spraying of toxic substances causes considerable damage to the ecosystem, is considered a crime against nature and is frowned upon in the cultivation of food crops anyway. As a result, at many affected locations, a cockchafer plague is accepted as a natural condition, for better or for worse. In concrete terms, this means: watching the activities of the may beetle, hoping for an imminent collapse of the mass reproduction and supporting the recovery of bare trees with good care.

    Fight cockchafer larvae with beneficial insects

    Cockchafer larvae can attack plant roots in the soil for up to four years. Hobby gardeners do not have to tolerate this devastating behavior. The discovery of grubs in the ground signals that a female cockchafer has chosen the garden as a nursery. The result is growth depression on trees, shrubs, perennials and yellow spots on the lawn. For a successful fight, get help from the realm of beneficial insects. The nematodes of the genus Heterorhabditis make short work of the devoured caterpillars. That is how it goes:

    1. The best time is in June, about 6 weeks after the cockchafer flight time
    2. Buy nematodes in specialist shops shortly before the planned control measure
    3. Dissolve nematodes supplied in clay granules in water according to the instructions provided
    4. Apply beneficial insects with the watering can and attached watering bar
    5. Keep infested beds or lawns slightly moist for several weeks
    6. Important: do not lime bedding soil or green area before or after (fertilizing is possible)

    The microscopic roundworms actively search for grubs. When they find what they are looking for, they enter the body and release a bacterium that is poisonous to the cockchafer larvae. A positive side effect: the genus of heterorhabditis nematodes does not spare the larvae of weevils either.Of course, the nematodes do not dare to approach a beetle pupa or an adult beetle.

    frequently asked Questions

    When do cockchafers fly?

    May beetles can be observed from mid-April

    When the ground warms up to 7°-8° Celsius in the first warm days of spring, the cockchafers that have hatched perk up and crawl out of the ground. Without much hesitation, they pump their wings several times and soar into the air. In the past, the natural spectacle could be admired in May. In the course of global warming, the first cockchafers are already flying through fields and forests from mid-April. Preferred flight time is during dusk.

    Can beetles sting?

    Cockchafers cannot sting. A pointed abdomen suggests that cockchafers could be equipped with a stinging device. In fact, it is the last visible abdominal segment that is part of the body structure for many beetles. When a cockchafer crawls over human skin, it holds on to it with small barbs on its six legs. This creates a feeling as if the big bug were stinging us.

    Are cockchafers poisonous to cats?

    Cockchafers are not poisonous to cats. If your house tiger devours one or the other buzzer, that is not dangerous. Of course, too many cockchafers should not be plastered over. The hard chitin shell could injure the walls of the stomach and intestines. If the beetles are heavy in the cat's stomach and the cat throws up the remains, it can be painful due to sharp-edged wing pieces.

    Are there still beetles?

    The cockchafer survived the decade-long chases with the chemical club until the 1970s. Since the mid-1980s there has been a steady recovery in the cockchafer population. However, cockchafer years and mass occurrences are limited to a few regions, such as the Upper Rhine or the forest areas in Lampertheim in southern Hesse. May beetles have become so rare in many areas that only the grandparent generations recognize the beetle when it comes flying.

    Can you fight cockchafers with nematodes?

    No, nematodes are lost against adult cockchafers. The nematodes have proven themselves as a biological control agent against cockchafer larvae because they parasitize the grubs and kill them in the process. The roundworms cannot penetrate the thick chitinous armor of an adult beetle. Nematodes are also ineffective against a beetle pupa.

    We found a starving may beetle in the apartment. What to do?

    If a cockchafer strays into the apartment, it is cut off from its natural food source. Within a short time the beetle is threatened with starvation. Even if you catch the cockchafer and release it outside, it's too weak to forage high in the treetops. By feeding the famished thug with oak or beech leaves for a while, you can feed your guest back to health and release them into freedom with renewed strength.

    What attracts cockchafers? What's keeping them away?

    Cockchafers prefer a habitat with sufficient food sources, such as deciduous trees, shrubs and grasses. The beetles like to settle where loose, sandy, permeable soil that is suitable for digging allows them to lay their eggs. If you do not want to attract cockchafers in the natural garden, we recommend regular maintenance work in the bed and lawn. Digging, weeding, raking or mowing are activities that cause unrest in the soil, which makes life hell for ravenous grubs.

    Are cockchafers a nuisance or a rarity?

    Cockchafers are both. After a near-exit in the 1970s, the legendary Beetle can now be admired again in some areas. Area-wide mass emergences were answered after the Second World War with ruthless means of combating them. Of course, the desire to eradicate the pests remained a pious wish. When the May beetle population dropped to its lowest point in the mid-1970s, there was a rethink in favor of the buzzing heralds of spring. Thanks to the ongoing recovery, cockchafer years with a plague character are now developing again. In many parts of Germany, however, the flight of a cockchafer is a rarity.

    tips

    Female cockchafers have an aversion to hard-working hobby gardeners. If the bed soil is raked and weeded regularly, it is far too restless to lay eggs. A lovingly tended lawn that is mowed weekly, scarified and fertilized annually is also despised as a nursery for voracious cockchafer larvae.

Category:

Animals in the garden