The canyon is home to several biting insects, including scorpions and bees, as well as several species of rodents and rattlesnakes. If you are allergic to beestings or insect bites, carry an EpiPen and be sure your hiking companions know how to use it. Prevent bites by watching where you place your hands and feet. Shake out clothing and bedding. Don’t pester or feed wildlife. Though snakebites are rare, they are almost always the result of people trying to handle snakes. Deer, bighorn sheep, coyotes, and rock squirrels have bitten people offering them handouts.

Rabies and plague aren’t uncommon in Arizona. Never handle a bat; if you see one during the day, it is quite likely infected with rabies. Keep your food supply secured when you are in camp: Ringtails, rodents, and ravens can get into packs even when they are hanging, so consider using animal-proof containers. Hantavirus, a deadly respiratory illness, can be transmitted by inhaling dust from rodent waste. If you discover that your zip-top bag of GORP has been chewed into, toss it out.

Some hikers feel safer carrying a bite extractor, which works for removing poison or stingers from insect bites as well as for snakebite venom. Any animal bite should be checked by a physician and monitored for signs of infection.