Oil Beetle

This oil beetle (tsuchihanmyou) was sitting on my doorstep when I came home last night. As you can see in the first photo, it played dead when I first picked it up.

Oil beetles are fascinating insects, and not just because of their unusual appearance (short elytra exposing most of the abdomen). They contain a poison (cantharin) in their hemolymph, which exudes from their leg joints when they are handled, and this substance causes skin blistering in humans (link to image), so these insects are also known as blister beetles. The same chemical (but extracted from other species) has been used for centuries as an aphrodisiac (spanish fly ointment) and is contained in wart removal products.

Another interesting point about the oil beetle is that it is parasitic on small solitary bees (hanabachi). The very active beetle larva (known as a tringulin) waits in a flower for a bee to visit, then clings onto the bee’s leg and gets carried to the nest, where it feeds on the bee’s eggs and store of pollen. For more information on the oil beetle’s fascinating life cycle, please read this. For information in Japanese, please look here.

oil beetle playing deadoil beetleoil beetleoil beetle

Coleoptera: Meloidae: Meloe coarctatus (hime tsuchihanmyou)
(I hope this identification is correct)
This is a male (see the pronounced bulge in the antenna)

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7 Responses to Oil Beetle

  1. Brit says:

    This was interesting to read! I love these beetles! I love insects too! How many species are in Japan?

  2. Nigel says:

    Hi Brit,
    Nobody knows exactly how many species of insects there are in Japan, but it’s been estimated that there may be as many as 100,000.
    11,000 species of beetles have been identified so far.
    That’s a lot!!
    Nigel

  3. Serge says:

    Very interesting and informative, thanks! I just saw one today (here in NB, Canada) did not know what it was until a personnel from Parks Canada told me about its name etc. Thus my web search lead me to this blog of yours.

    If you like I can send you a photo.

    Anyhow, take care.

    Serge

  4. Laura says:

    Wow. Saw one of these on my couch tonight. I live in Missouri, USA. Your pictures really capture it!

  5. Olivia says:

    I live in the Eastern Sierra Mountains of Nevada, a few hours from Reno. I recently found one of these stalking my dogs around my front yard. Scary.

  6. luki says:

    This bug is very usually, It is a crop injurious insect. So you must kill it .

  7. pete says:

    @luki or you just observe it without even toughing it, or not handle it with bare hands 😉

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