Ticks are obligate blood-sucking ectoparasites (external parasites) that require an animal host to survive and reproduce. Depending on the species, several ticks may have different hosts of warm-blooded creatures, such as humans, mammals, birds, reptiles, and amphibians. There are about 867 species of ticks distributed worldwide, 80 USA species, and 13 Minnesota species. People react differently to tick bites. Typical bites normally trigger skin irritation, which is itchy. However, in animal farms, severe infestations on animals can cause anemia, weight loss, and even death from the consumption of large quantities of blood. Besides itching, a few species of ticks (not more than 10%) are vectors of a large range of disease-causing pathogens of domestic animals and humans. In North America, the pathogens associated with the following diseases can be transmitted by tick bites: Lyme disease, human granulocytic and monocytic ehrlichiosis, babesiosis, relapsing fever, Rocky Mountain spotted fever, Colorado tick fever, tularemia, Query fever, and tick paralysis. Three species of ticks are likely to be encountered by people: black-legged (deer) tick, American dog ticks, and brown dog ticks. There are three major disease-causing organisms are transmitted through the bite of an infected deer tick: Lyme disease, human anaplasmosis, and babesiosis. The American dog tick is responsible for transmitting Rickettsia rickettsii, which causes Rocky Mountain spotted fever in humans. This tick can also transmit tularemia. Brown dog ticks are not known to transmit diseases to humans but may transmit disease among dogs. To avoid tick bites, it is important to be prepared before it is too late. Like mosquito and other insects, the onset of the tick's season is a temperature-dependent issue - the warmer the spring temperature, the faster insect pests can develop. Therefore, if you live in known tick-infested areas, watch the weather and be prepared for these bloodsuckers. Usually, adults of deer ticks (the most common Lyme Disease tick vectors) can emerge in patchy snow at temperature of 40°F and more.