Colorado is home to approximately 80 different species of fleas, according to cooperative extension agents at Colorado State University. But fleas rarely pose a problem to pets in the state, thanks to the dry climate. Fleas need moisture to develop, and even inside homes in Colorado, humidity is usually low. However, pets coming from other states with higher humidity can bring flea infestations with them, and wild animals can also harbor the blood-sucking pests.
The average altitude in Colorado is 6,800 feet above sea level, report researchers at the Colorado Climate Center. The high elevation, coupled with the state's location in the middle latitudes of the interior continent, make for average annual relative humidity levels that range from 63 percent in the morning to 40 percent in the afternoon in Denver, according to data collected by the National Climactic Data Center. These humidity levels are low compared to average annual humidity levels in such places as Orlando, Florida (90 percent in the morning and 55 percent in the afternoon) or Quillayute, Washington (93 percent in the morning, 74 percent in the afternoon).
Although fleas are less common in pets born and raised in Colorado, pets that are relocated to the state from other areas can bring a flea infestation with them. While they have been known to survive in a Colorado household if the humidity is high enough, this is rare and, for the most part, fleas found in the state are hosted by wild animals.
Wild Animals and Fleas
If a home flea invasion does occur in Colorado and the fleas didn't come from relocated pets, the most common culprit are fox or skunks nesting in the area. Fleas need a host to survive. If the flea-laden wild animal abandons its den, any fleas left behind scatter and can find a new host in a nearby family pet or even humans.
Fleas pose a potentially fatal problem in Colorado because some of the species in the state carry the bacterium Yersenia pestis, which causes the rare but deadly plague. The rock squirrel flea is the primary carrier of this microorganism and is usually hosted by rock squirrels, prairie dogs, wood rats, and other rodents that inhabit burrows or stick nests.
Fortunately for Coloradans, the human flea is the most common flea found in the state and it is not a carrier of the plague-causing bacterium, so the chances of contacting the plague are relatively low, Typically, only one case is reported annually in the state.