Ticks, poison oak, and stinging nettles—these three are far worse than a whole convention of snakes, mountain lions, and bears. But you can avoid them with a little common sense, and here's how:

TICKS:

The easiest way to stay clear of ticks is to wear long pants and long sleeves, and to check your clothes when you take them off. If it's too hot to be covered up in long sleeves, just make sure you look yourself over thoroughly when you leave the trail and remove anything that's crawling on you. (A good friend can assist you in this pursuit.) Be especially wary of ticks in the winter and spring months, when they are most prevalent.

Remember that if you find a tick on your skin, the larger brown ones are harmless. Of the nearly 50 varieties of ticks present in California, only the tiny brown-black ones, called the western black-legged tick, can carry Lyme disease. If you find a tick on you and he's actually biting into your skin (not just crawling around), you should remove the tick, put it in a plastic bag, and take it to your doctor for examination to see if it is carrying Lyme disease. The best way to remove a tick is by grasping it as close to your skin as possible, then pulling it gently and slowly straight out, without twisting or jerking it. A tweezers works well for the job, and many Swiss army knives include a tweezers.

Rangers also warn people that if they've been in the outdoors, and then a few days or a week later start to experience headaches, fever, nausea, or rashes, they should see a doctor immediately and tell him or her that they are concerned about possible exposure to ticks and Lyme disease. Caught in its early stages, Lyme disease is easily treated with antibioticks.

POISON OAK:

That old Boy Scout motto holds true: Leaves of three, let them be. Learn to recognize and avoid Toxicodendron diversilobum, which produces an itching rash that can last for weeks. The shiny-leaved shrub grows with maddening exuberance in California's coastal and mountain canyons below 5,000 feet. If you can't readily identify poison oak, stay away from vine-like plants that have three leaves. Remember that in spring and summer poison oak looks a little like wild blackberry bushes and often has red colors in its leaves as well as green. In late fall and winter, poison oak goes dormant and loses its leaves, but it's still potent.

Avoid poison oak by staying on the trail and wearing long pants and long sleeves in areas that are encroached by it. If you prefer to wear shorts when you hike, try a pair of the convertible pants that are found at most outdoor stores. These are lightweight pants with legs that zip off to convert to shorts. Put the pant legs on when you come to an area that is rife with poison oak. If you accidentally touch the plant with your bare skin, wash off the area as soon as possible. Waiting until you get home five hours later may be too late, so wash as best as you can using stream water or whatever is available.

Hikers who are highly allergic to poison oak should consider carrying packages of Technu, a poison oak wash-off treatment that is sold in bottles or individual foil packs. Carrying one little package could save you weeks of scratching.

Remember that if poison oak touches your clothes, your pack, or even your dog, and then you handle any of those items, the oils can rub off on to your skin. Wash everything thoroughly as soon as you get home.

STINGING NETTLES:

Ouch! This member of the nettle family is bright green, can grow to six feet tall, and is covered with tiny stinging hairs. When you brush against one it zaps you with its poison, which feels like a mild bee sting. The sting can last for up to 24 hours. Stinging nettles grow near creeks or streams, and they're usually found in tandem with deer ferns and sword ferns. If the nettles zing you, grab a nearby fern leaf and rub the underside of it against the stinging area. It sounds odd, but it sometimes helps to take the sting out. If it doesn't help, you're out of luck and you just have to wait for the sting to go away.