Praying mantises are found in Wisconsin, captivating observers with their distinctive appearance and predatory habits. These insects have established a presence throughout the state.
Mantises Present in Wisconsin
Wisconsin is home to a few species of mantises, primarily the non-native Chinese Mantis (Tenodera sinensis) and the European Mantis (Mantis religiosa). The Chinese mantis is larger, three to five inches long, and can be bright green, light brown, or a combination of both, with long, slender wings extending beyond its abdomen. The European mantis is smaller, two to three inches long, and can be pale green or tan. A distinguishing feature of the European mantis is a black-ringed white spot inside its front legs, near the throat. The Chinese and European mantises are the most commonly encountered species in the state.
How Mantises Arrived in Wisconsin
Mantises arrived in Wisconsin through intentional introductions for pest control. The European mantis was introduced to the United States around 1899 on imported nursery stock. The Chinese mantis also arrived, believed to be accidental, on a plant shipment to Pennsylvania in 1896. From the 1930s, egg cases of both European and Chinese mantises were purposefully imported and sold across the country, including in Wisconsin, as biological control agents for garden pests. This commercial distribution contributed to their establishment and spread.
Mantises in the Wisconsin Ecosystem
Mantises are ambush predators, using powerful, spiny forelegs to capture prey. They are generalist feeders, consuming nearly any insect they can overpower, including flies, beetles, crickets, moths, and grasshoppers. Larger mantises can even prey on small frogs, lizards, or hummingbirds. The ecological impact of these non-native mantises in Wisconsin is a subject of ongoing discussion. While they consume garden pests, they also prey indiscriminately on beneficial native insects, including pollinators like butterflies and bees, raising concerns about their effect on local insect populations and the broader ecosystem.
When and Where to Spot Mantises
Observing mantises in Wisconsin is most common during late summer and fall, when adults are most active and have reached their full size, making them easier to spot. Their life cycle involves eggs overwintering in hardened cases (oothecae), with nymphs hatching in spring and maturing by late summer. Mantises prefer habitats with dense vegetation, such as gardens, meadows, and areas with tall grasses and shrubbery. Their camouflage allows them to blend with their surroundings, making them challenging to find despite their size. They are often found on plant stems or leaves, ready to ambush prey.