Centipedes and millipedes can have sharp claws and some have poisons bites. Especially when traveling in the tropics watch out for these. If they crawl onto your skin brush them off in the direction they are moving. Also wear underwear at night so they don’t decide to nestle in your crotch for warmth.
There are killer bee swarms in Africa and Costa Rica and the disaster movie men are hoping they’ll spread further north. Bees will normally leave you alone though, just don’t mess with their honey. Hornets are much more serious though and can be quite aggressive – if these larger, ferocious-looking insects get stirred up make a run for the nearest bath tub of cold water.
Ticks can drop off animals or bushes onto the skin in the tropics. They bite into you and suck your blood. Don’t pull them off as this can cause an infection – instead make them drop off with heat, petrol, alcohol or hot water.
Leeches do the same thing and hang out in moist, tropical areas. Don’t pull them off either but remove with fire or salt. They often carry infections so chew some garlic afterwards.
There are various worms that bury into your skin, often from treading on sand where dogs have pissed. These will begin to zigzag through your skin and lay eggs. It’s pretty gory but you need to smother the area in ice to kill them and anaesthetize the area.
Then get a good friend to open the path of the worm with a sterile needle or thorn and take out the worm and its eggs. These will look like small white dots the size of a flea.
And if traveling in the Amazon, never piss in river water – there exists a fish called the Candiru which can swim up your urethra until its dorsal spine gets stuck.