While scorpions are common in southern parts of the US, they aren’t native to Wisconsin or the Upper Midwest. Occasionally, they show up in the state as hitchhikers from other locations. In the last decade, I’ve seen only a handful of cases where scorpions were spotted in the Badger state. Interestingly, I’ve now had three reports of live scorpions submitted to the UW Insect Diagnostic Lab this year—from Milwaukee, Madison, and recently from Prairie du Chien (as shown in the video clip below). In the rare cases that scorpions do make an appearance, they tend to be the striped bark scorpion (Centruroides vittatus) or a close relative.
The striped bark scorpion is one of the most commonly encountered scorpions in the United States. This arachnid can reach lengths of roughly 2½ inches. It typically has a beige or yellowish body with two dark stripes running down its back—hence the name. They also have a dark triangular pattern near the eyes at the front of the body, which can help distinguish them from other species.
The striped bark scorpion is primarily found in the south-central United States, with most sightings coming from Texas. Its range extends west to New Mexico and eastern Colorado, and as far northeast as the St. Louis area. The species is also present in Mexico. Occasional sightings have been reported outside this typical range. In their natural habitat, these scorpions prefer secluded spots such as under loose tree bark, logs, rocks, and woodpiles. They may also seek shelter near buildings and can inadvertently wander indoors.
Like many other scorpions, striped bark scorpions are nocturnal and are mostly active after dark. These arachnids are generalist predators, hunting insects and other small arthropods. They use their pedipalps (“pincers”) and telson (“stinger”) to subdue prey. While technically venomous, the striped bark scorpion’s venom is relatively mild and not considered medically dangerous to humans. However, stings from this species can still be quite painful.
Do the three reports of live scorpions mean that these creatures are becoming more common in our area? No, not necessarily. While it’s hard to tell how the range of scorpions may push northwards with climate change, we’re still well north of the native range of species like the striped bark scorpion. The vast majority of Wisconsinites will never see one of these creatures in the state outside of captivity. If anything, the three cases this year may simply illustrate how scorpions can be moved around by humans under the right conditions.
