Since the earliest days of mankind, we’ve excelled at exploring and expanding our presence to nearly every spot on the map. With all our wanderlust, we’ve been equally adept at taking other species with us as we go—often with unintended consequences.
In some situations, species have been deliberately moved by humans: livestock to the new world, the introduction of birds from Shakespeare’s plays into Central Park, and even the notorious gypsy moth was transported from Europe in a failed attempt at an American silkmoth industry. On top of that, there’s an extraordinarily long list of species that have been accidentally moved, with significant impacts. Stowaway rats on the ships of European explorers and traders would be one of the most notorious examples. Rats introduced to new island environments wreak havoc on native birds and reptiles by devouring vulnerable eggs. Insects have also been transported around the globe with devastating results and some of North America’s most important and emerging insect pests originate elsewhere on the planet: Japanese beetle, emerald ash borer, brown marmorated stink bug, and the spotted lanternfly.
One of the insects best adapted to follow humans is the notorious mosquito. Certain mosquito species (peridomestic species) possess traits that allow them to take advantage of conditions in areas disturbed by humans and thrive in those spots. With humans came environmental modification, construction, and discarded trash of one kind or another. Some mosquitoes might have originally relied on the water pooled in natural containers, such as rotted out tree stumps to reproduce, but can just as easily take advantage of water-filled containers, ditches, and other artificial habitats.
In modern times, automotive tires have become a key habitat for certain mosquito species. Tires not only are perfect objects for holding water for extended periods, but they also provide the dark, sheltered habitat favored by some female mosquitoes looking to lay eggs. Tires are an important way for mosquitoes, like the Asian Tiger Mosquito (Aedes albopictus) to be moved into and around the US (including the Midwest). Other species, like the Asian Rock Pool Mosquito (Ochlerotatus japonicus), are also easily transported in human materials.
A recent case at the UW Insect Diagnostic Lab illustrates the ease with which non-native mosquitoes can be moved around the country. In the first part of 2018, stores have been selling hyacinth bulbs in vases pre-filled with water as a way to force the bulbs to bloom into a flash of color during the dreary winter months. In a recent discovery in southeastern Wisconsin, a vase purchased at a local store ended up yielding half a dozen larvae of the non-native Asian rock pool mosquito. The exact origin of the mosquitoes isn’t known at this time.
These mosquitoes won’t be much of a concern in the grand scheme of things as Ochlerotatus japonicus has been present in Wisconsin for over a decade and is already established here. However, such cases do leave open the possibility of non-native mosquitoes being moved into parts of the country where these pests have not been encountered before. Where humans go, pests will boldly follow.