Black and blue oil beetle
| Black and blue oil beetle | ||||||||||||
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Black-and- blue oil beetle ( Meloe proscarabaeus ), male |
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| Meloe proscarabaeus | ||||||||||||
| Linnaeus , 1758 |
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The black and blue oil beetle ( Meloe proscarabaeus ), also known as the black mayworm , is a beetle from the family of the oil beetles (Meloidae).
features
The beetles are 11 to 35 millimeters long. The chitin armor shines black-blue all over the body, it is elongated, yet not slim, but rather stocky. The head and the pronotum are roughly dotted and shimmer in the spaces between the dots. The finely granulated elytra are greatly shortened over the distended abdomen, slightly overlap at the base (unusual in beetles!) And gape at the ends so that a large part of the abdomen is freely visible. Both the legs and the thread-like antennae are quite long and strong. The antennae of the males are clearly bent in the middle.
distribution
The beetles are found in Europe , east to Central Asia . They live in sandy and open places. The beetles are still quite common regionally in Central Europe. Overall, however, the population is decreasing as the beetle's habitat, especially meadows, is increasingly changing. That is why the black-and-blue oil beetles in Germany are classified as endangered in the Red List of Threatened Species (3). You can find them from April to June.
Way of life
The diurnal animals usually stay on the ground. They feed on parts of plants. In case of danger, they use a yellow defense secretion containing the toxin cantharidin from their knee joints to deter enemies .
After mating, a female lays 3–5 cm long eggs 3–5 cm in the ground 5–6 times at intervals of 1–2 weeks each time 3000–9500 0.9–1.3 mm long eggs. The eggs make up 30-45% of its weight, which is why it has to eat again and again. The eggs overwinter and the larvae, called tri-claws ( Triungulinus ), hatch in the next spring. They are yellow to orange and shorter than 2 mm, in contrast to the violet oil beetle ( Meloe violaceus ), which are 2 to 2.5 mm long. The three-claws climb onto flowers and then cling to flower visitors. If it is not the right species, such as honey bees , the larva will die. Suitable hosts are solitary bees , their associated cuckoo bees and parasites of the genus Volucella . The host involuntarily takes the larva into its den, where the latter fights over the host's larvae. It then sheds its skin into a short-legged, maggot-like and blind secondary larva L2, which eats the honey pollen pulp and sheds its skin three times to the secondary larva L5. Then it wanders out of the nest and sheds its skin to a dummy L6, which hibernates. In the spring a tertiary larva L7 hatches from it, which probably does not eat any food. Only then does it pupate and the finished beetle hatches from March to May. The females eat a lot and can increase their weight sixfold (maturation feed). They then mate several times.
Another way of distribution of the three claws is their accumulation at the tips of blades of grass. The orange-yellow larvae form clumps during the day that attract bees. When they notice their mistake, a few larvae have already transferred. This behavior has been observed in meadows where there would have been enough flowers available.
Harmful effect
The black-and-blue oil beetle occurs in Egypt as a pest in agriculture, where it has only been detected since 1976. Of the four plants tested, both sexes prefer lettuce ( Lactuca sativa ), followed by broad beans ( Vicia faba ), Egyptian clover ( Trifolium alexandrinum ) and least of all peas ( Pisum sativum ).
Similar Art
- Violet oil beetle ( Meloe violaceus ). While the base of the pronotum is straight in the black and blue oil beetle, it is indented in the purple oil beetle.
Insect of the year 2020
On November 27, 2019, the species was named Insect of the Year in a joint declaration by the Senckenberg Society for Nature Research and the Federal Agency for Nature Conservation.
Web links
literature
- Heiko Bellmann : The New Cosmos Insect Guide. Franckh-Kosmos Verlags-GmbH & Co, Stuttgart 1999, ISBN 3-440-07682-2 .
- Severa Harde: The Beetle Leader Cosmos. The Central European beetle. Franckh-Kosmos Verlags-GmbH & Co, Stuttgart 2000, ISBN 3-440-06959-1 .
Individual evidence
- ^ A b Bernhard Klausnitzer: Observations on the way of life of Meloe proscarabaeus Linnaeus, 1758 (Coleoptera: Meloidae) . In: Naturmuseum Südtirol (Ed.): Gredleriana . No. 5 , 2005, ISSN 1593-5205 , p. 209–216 ( PDF on ZOBODAT [accessed March 8, 2015]).
- ↑ KS Ghoneim, AA Abdel-Khaliq, AS Bream, DM Emam: Food preference and consumption by adults of black blister beetle Meloe proscarabaeus (Coleoptera: Meloidae) on different host plants . In: International Journal of Agricultural Science Research . tape 1 , no. 2 . Academe Research Journals, November 2012, ISSN 2327-3321 , pp. 16–23 ( researchgate.net [PDF; accessed March 8, 2015]).
- ↑ Identification key for flora and fauna in Rhineland-Palatinate: Beetles in and around Rhineland-Palatinate. ArtenInfo portal , accessed on March 26, 2019.
- ↑ Love potions, poisonous murders and plasters in labor: the black-and-blue oil beetle is insect of the year 2020. Federal Agency for Nature Conservation , November 27, 2019.