Japanese Darkling Beetle, Mushrooms, and a Warning

2023 October 8

Sandy photographed this darkling beetle in Japan on August 16, 2023. It was the first insect that they saw on their trip, and it was about the size of the last joint of her little finger. It looks a lot like the darkling beetles we have in Houghton, except that its eyes were peculiarly shaped. It looks like the eyes are looking straight up, instead of more to the side like most other insects.

I believe that this is Plesiophthalmus nigrocyaneus, which look just like this. They are very common in Japan, and are known for walking around on the trunks of trees where theyh are easy to see. Both the adults and their larvae eat debris from rotting trees.

Then a couple of days later, they saw a big wolf spider fighting with a skink (a type of lizard). It unfortunately happened too fast for them to get a good picture of. The wolf spider had an egg sac that she was carrying, and the skink ran up, tussled with her until it got the egg sac, and then ran off with it.

At about the same time they found these cute, tiny mushrooms. This was near Nikko, which is warm and wet during the summer, and therefore a perfect environment for this sort of thing.

And, of course, there are other things that like a warm, wet environment. This warning sign was on a nature trail:

And what was it warning people about? Terrestrial leeches! Running it through Google Lens, this is approximately what it says[1]:

“Yamabiru[2] is not poisonous. It reacts to body temperature, carbon dioxide (exhaled air), vibration (movement such as walking), light, and smell. It easily finds small gaps in clothing as it crawls up to look for a place to suck blood. As a countermeasure, wear long sleeves and long pants. Please check your feet frequently. If you find a leech, remove it immediately by covering with salt or insect repellent, and dispose of it. Pinch and suck the wound to squeeze out the hirudin[3] injected by leeches, rinse your mouth out with water, and apply insect bite and itch medicine. If you continue to experience symptoms such as itching or hives, pelase consult a dermatologist. – Nikko Futarasan Shrine”

[1] That is not verbatim exactly what Google said, because some of the translation was a bit garbled and unclear, but that is my best guess of what it was intended to say.

[2] Yamabiru are Japanese mountain leeches, Haemadipsa zeylanica. They have been moving into more populated parts of Japan in recent years, and are evidently annoying a lot of people.

[3] Hirudin is the anticoagulant that leeches use to keep the blood flowing freely when they bite. I am honestly not so sure about some of the advice on this poster. Things injected into the body travel faster than one might think, and I doubt that the hirudin will stay sufficiently close to the wound that it would be practical to suck it out. Still, it probably won’t do any harm.

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