YAKU MACAQUES ヤクザル
1. They are wild.
2. They have very large pointy teeth.
There are around 7000 of them roaming the mountains and can often be seen along the side of the mountain roads and on the trails. Sometimes hanging around the villages watching traffic.
YAKUSHIKA DEER ヤクシカ
Any size, shape and colour you could wish for.
A variety of strange looking spiders inhabit the forest.
Surprisingly common on the mountain slopes.
For more information about the wildlife on Yakushima - check out the one and only Yakumonkey Guide to Yakushima
Is that hornet the notorious Japanese giant hornet (Vespa mandarinia japonica)? Speaking as a waspophobe who's going to be visiting Yakushima in May/June, how worried should I be?
Yes, it's the Vespa mandarinia japonica otherwise known as the Suzumebachi hornet. They don't normally cause any problems for visitors but here's some of the advice from my book if you're at all worried - keep to the paths, don't wear black and avoid strong perfumes.
What is the reason behind not wearing black? I've read other places not to wear bright clothing bc insects will mistake you for a flower, but haven't heard about the not wearing black thing before.
I believe it is because black is the color they associate with their natural predators which are usually large dark-looking mammals.
...just how common is it to find a leech sucking away at your shin?
Very common! But more so in rainy season. Usually the only reason you know you had a leech is when you later take your socks off and there's blood on them. The leech is normally long gone.
Outside of what's listed already, are there any year-round or seasonal biters (like mosquitoes)? Would you recommend insect repellent?