What insect can kill a person?

It is only a few centimeters tall, but can kill a person with its poison: the oil beetle was recently voted “Insect of the Year 2020”. The 104th episode of the OVB series “Safari at home” deals with this shimmering animal in the truest sense of the word.

Rosenheim - Anyone who walks attentively at the edge of the forest in April and May can spot an extremely conspicuous beetle. He crawls clumsily and lazily through grass and flowers in his shimmering blue dress. We're talking about the oil beetle.

The female can reach an impressive two to four centimeters in size. The males usually stay a little smaller. The shortened wing-coverts gape apart, the hind wings have completely rationalized away the evolution. The sedate beetle no longer needs to fly - it has found other ways of survival.

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The adult beetles produce highly toxic antibodies that are contained in their blood (the hemolymph). In the event of danger, they can excrete an oily liquid containing the poison cantharidin, especially at the knee joints. This protects the beetle above all against ants and ground beetles. Other predators such as hedgehogs and birds are immune to the poison. Again, quite a few insects are literally attracted by the toxin cantharidin. They seek out the oil beetle (Meloae violaceus) in a targeted manner - dead or alive - eat it or tap it in order to then organize their own defense with the poison they have ingested.


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On closer inspection, one can see, for example, how many small midges, i.e. tiny biting insects, take up the body fluid of the oil beetle in a targeted manner at the membranous areas between the abdominal rings. Just as it is not possible for humans to keep these tormentors at bay, the attempts of the oil beetle to defend themselves against these annoying parasites are also in vain.

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May worms, as the oil beetles are also called, drag a huge number of eggs with them in their abdomen in spring. Each female produces between 4,000 and 10,000. This makes the rear part look misshapen and swollen.

This large overproduction is probably necessary because only very few succeed in the highly specialized development of larvae to adult beetles. Connoisseurs estimate that only every thousandth egg becomes an adult individual. In nature, high fertility always occurs when there is a strong influence of predators or when the development is very complicated.

Parasitic larvae

First, the female lays small piles of eggs randomly in the earth. You have to know that oil beetle larvae are parasitic. After hatching from the egg, you have to manage to get into a nest of a solitary wild bee. The development of the three different larval stages also have three different shapes with subsequent pupation.

When the larvae hatch from the eggs, they are around two millimeters in size, mobile, six-legged and yellow. You climb the blooms of various flowers such as wood anemones, dandelions and buttercups. In this first larval stage, nature has endowed them with a special feature. There are three claw-like hooks on each of its six legs.

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The little three-clawed claw, as the larvae are also called, can lurk on the flower for up to three weeks without catching up on its honey-collecting conveyor (phoresy). Ideally, this is a wild bee, but it can also be a hover fly or other insects, which ultimately means certain death. Because the larva can only develop in the wild bee.

If it is a wild bee with the right conditions, the insect will carry this “louse in fur” into its nest cell. But only when the bee has laid an egg in the supplies recorded for its own larva does the three-clawed man let go of his taxi and jump over to the egg. This jump carries the great risk of drowning in honey if it misses the egg.

Hibernating dummy doll

If the jump worked, the three claws first eat the bee's egg. After that, with the first moult, it changes into a completely different, boat-shaped, maggot-like, second larval form that floats on the honey. She immediately gets to grips with the nutritious honey and pollen that were actually intended for the bee larvae. When the supply is used up, the larva leaves the cell and sheds its skin in the ground to form a hibernating dummy pupa (pseudonymph).

In this it sheds its skin to the third larva (tertiary larva). Pupation into a beetle takes place four weeks later. Such a cumbersome development over several larval stages is called “over-transformation” (hypermetamorphosis). She explains again the high number of eggs that the female initially laid, because all the previous descriptions of each transformation are certainly associated with great losses. After such a long and complicated larval period, the beetle's lifespan - after it has given off offspring - is over after one to two months. The adult beetle is a pure herbivore that feeds on wild garlic, celandine and many other flowering plants.

Oil beetles are not common here. Most of the time I found them in the alluvial forest. Incidentally, the blue-black oil beetle has been voted “Insect of the Year 2020”. The poison cantharidin, which the beetle actually releases when touched (reflex bleeding) to ward off predators, also has an irritating effect on human skin and can lead to painful blistering. The toxicity of this beetle was already known in ancient times. It was therefore used as a healing animal, but also for poisonous murders. The poison from just one oil beetle is enough to kill a person.

From poisoning to the love potion

The aphrodisiac properties of the substance also became known. Dried, pounded in a mortar and prepared in honey, the large oil beetle was one of the most famous "love potions" for increasing sexual potency. However, the effective and lethal dose are very close to one another, so that some longed-for cohabitation became an unforeseen hike into the afterlife. The poison was misused for executions in ancient Greece, but murders with the beetle poison are also known up to modern times. If you find an oil beetle, you should keep your hands off it. "