JACKI LYDEN, HOST:
OK, you don't have to see to recognize this sound.
(SOUNDBITE OF SWARMING BUGS)
LYDEN: Swarming bugs. It's part of what makes the thrum of life in the heart of summer. More and more, though, we're coming into contact with the nasty, bloodsucking kind of bugs, namely mosquitoes and ticks. One relative newcomer prowling the scene is the Asian tiger mosquito.
BRIAN ALLAN: It's black with white stripes. It's actually - if I could go out on a limb here - a very beautiful mosquito.
LYDEN: Spoken like a true entomologist. That's Brian Allan, assistant professor at the University of Illinois Urbana-Champaign. But swashbuckling stripes aside, the Asian tiger mosquito could also have been named for its aggressiveness, biting fast enough to escape swatting.
ALLAN: It's also very adaptable in terms of the types of habitats it occupies. It can live inside houses as well as outside of houses.
LYDEN: And it thrives in tropical climates as well as temperate ones. So how did the Asian tiger mosquitoes get here? They probably hatched in the standing water inside used tires shipped over from Asia in the 1980s. And since then, they've only been spreading, outcompeting native mosquitoes in urban and suburban areas in the South, the Midwest, on the East Coast and Hawaii causing outbreaks of the dengue virus.
ALLAN: Many diseases are starting to occur in places where they simply didn't occur previously.
LYDEN: Such as the West Nile virus. But far more common in this country is Lyme disease.
ALLAN: The distributions of ticks and the distributions of the pathogens they transmit to humans are increasing in many parts of North America.
LYDEN: Notably, the blacklegged tick, better known as the deer tick.
ALLAN: In recent history, it had two areas in which it generally occurred: the Northeastern United States and the Upper Midwest.
LYDEN: And over the years, those two areas have grown so big they're practically touching. Part of the problem is us. As we take up more room, deer and mice - tasty tick hosts - are being pushed into our space, where they face fewer natural predators.
ALLAN: And so these really large animal populations may be more conducive then to the establishment of these ticks in new areas.
LYDEN: Another factor, climate change.
ALLAN: Warmer winters could result in greater over-winter survival of both ticks and mosquitoes, and by that exacerbate the prevalence of disease in humans.
LYDEN: But this expanding bug population is emblematic of a bigger problems, says Allan.
ALLAN: We're having a problem with invasive species of all varieties. And so this is something of a overlooked crisis, in terms of its biological impact.
LYDEN: Global commerce, expanding development, even the pet trade, are all factors.
ALLAN: They all, in some sense or another, tie to human globalization and the point that human movements and human connectedness are greater now than at any point in human history. And there are some real biological consequences for that.
LYDEN: Our ever closer ties creating a network for hungry ticks and mosquitoes to connect with us.
(SOUNDBITE OF MUSIC)