While no ectoparasite is favored, I think that the ultimate hitchhiker and of the more sneaky ones is the tick!
When they first start out they no larger than a comma on a page. By the time you see them crawling on your clothes or your pet they have feed, breed and are moving on to a new host. Unlike the flea, which is more aggressive about finding a host, the tick will wait patiently on a blade of grass, a leaf or flower waiting for an unsuspecting host to come along. Imagine if you will an eight legged arachnid with his thumb out waiting for a ride as you and your pet walk through the yard, bike/nature trail.
While ticks do not jump like fleas, when they find a new host they are just as aggressive to feed and reproduce. They are related to spiders because they have eight legs, and one female tick can produce up to 100 to 3-6 thousand eggs(depending on the species). Ticks are live without a host for up to 3 years, they can cause all types of problems for pets and people transmitting such things as lyme disease, and rocky mountain spotted fever.
The way to protect you and your pet is cut down high grass and weeds in your yard. If you have a lawn service, have the treat your yard, for fleas, ticks and mosquitos. If you treat your yard yourself, you can pick up a hose end yard insect killer at you local hardware store. The treatment usually last for 4 weeks under normal conditions. When you are working outdoors make sure that you tuck your pant legs in your socks(white) and spray yourself with an insect repellant especially around your shoes and socks. Keep your pet current on a good quality flea and tick preventative like: Frontline Plus, K-9 Advantage, Revolution for dogs, Advantage for cats. Be sure to use the right product weight for your pet and DO NOT use a flea/tick product for dogs on cats, it will kill your cat!
When you come in from outdoors make sure you check your pet thoroughly for these pests. Before they imbed themselves in the skin you will see something that looks like a watermelon seed(depending on your area) with legs on you or your pet. If you are using a quality flea and tick preventative and you find a tick on your pet don't panic! Remember that the preventative will kill them, but it will NOT prevent them from imbedding on your pet. Get a pair of tweezers and get as close to the skin as possible without pinching the pets skin. Rock the body of the tick back and forth gently until the insect comes out. It is not uncommon to see a patch of white flesh come out when you remove the tick properly. Do NOT squeeze or "pop" the tick, the fluids can be toxic! If that happens, clean your hands thoroughly with an antibacterial soap and rinse them with rubbing alcohol. Clean the tweezers in a small sandwich bag with a cap full or two of rubbing alcohol. After you have removed the tick, place it in a small sandwich bag with a cotton ball wet with rubbing alcohol. You can take the tick to the vet for examination, the rubbing alcohol cotton ball will suffocate the tick. DO NOT try to burn the tick off the pet, you can injure the pet, and it places the tick in a defensive mode, it will dig in for survival.
Some pets my have an allergic reaction to the saliva or the removal of the parasite, talk to your vet or have your mobile stylist give your pet an medicated bath to soothe the skin.