Mantid Madness

It’s a common theme in history that invasive species were introduced to the United States either on accident or on purpose for a good purpose. Melaleuca or paper-bark trees (Melaleuca quinquenervia) were introduced to the Everglades to dry it up and stabilize the soil. Now massive stands of these trees outcompete native tree species in Florida. Japanese barberry (Berberis thunbergii) was introduced as an ornamental plant in the mid- to late-1800s and has since aggressively spread throughout the U.S. after being established in New York.

Good gone wrong

This same cycle of good-gone-wrong occurs in the animal kingdom as well. An example we can see in our front lawns is the Chinese mantis (Tenodera sinensis). Introduced from Asia by accident and further seen as a natural pest control measure, Chinese mantises have since run rampant across the United States, eating anything but what they were brought here to. These cryptic predators eat native insects such as bumblebees, grasshoppers, butterflies, and beetles. Some reports have shown they can sometimes ambush hummingbirds at feeders as well.

Left: an ootheca laid in October by Welty’s current resident Chinese mantis (Right).

Knowledge is power

To combat these nuisance insects and protect native species, it is helpful to know a bit about the life cycle of a mantis. We’re all probably familiar with the seemingly innocent faces of adult mantids: their quiet, graceful dispositions fit the common name of “praying mantis.” Most species found in the United States are cannibalistic (i.e., females eat the males after mating, hatchlings eat each other), so most adult mantids that are found are likely female. It’s convenient for the females that they can reach up to 10-times heavier than males, so the females are more successful in overpowering their enemies. 

Since their arrival, Chinese mantises have run rampant across the US…

Two weeks after mating, a female can lay over 100 eggs in an ootheca, which directly translates from Greek as “covered egg.” This foam-looking blob on a stem (see photo) is a massive indicator of mantid presence (the ootheca is one of the easier ways of identifying species as well). An ootheca is usually laid in the late fall and overwinters to later hatch in the spring. The problem, though, is native mantids such as the Carolina mantis (Stagmomantis carolina) are on the same laying and hatching timeline, but Chinese mantis oothecae are up to three times larger than Carolina mantis oothecae. When eggs hatch, the nymphs look like miniature adults as they undergo incomplete metamorphosis (complete metamorphosis would be a caterpillar changing to a butterfly).

…eating anything but what they were brought here to eat.

Humane ways to remove a Chinese mantis ootheca when you see one is to clip the stem where the ootheca is placed and bury it in the ground away from the garden.

Possible lookalikes

It’s important to note that not all mantis species are invasive. The Carolina mantis is native to the southern U.S., but the European mantis (Mantis religiosa) and narrow-winged mantis (Tenodera angustipennis) along with the Chinese mantis were introduced from Asia. The common denominator is their first introductions were all accidents: the narrow-winged mantis was first documented in the U.S. in 1933, the European mantis was introduced in 1899, and the Chinese mantis was introduced in 1896.

Things to consider when you encounter a mantis:

  • All mantids have sharp spikes on their forelimbs to help attack prey (see photo; be careful of them when attempting to handle a mantid!)
  • The Chinese mantis is the largest species of mantis in the United States
    • Carolina mantises are much smaller than Chinese mantises
  • Chinese mantis antennae are closer together on their heads than other species (see photo)
  • Chinese mantises have noticeable stripes on their faces (see photo)
  • The spot between the front legs of a Chinese mantis is yellow (see photo)
    • European mantises will have orange between the front legs
  • Adult female Carolina mantises have short wings that do not extend past their bodies
  • Gravid (with eggs) female mantids will have distended abdomens

Found a mantis and still not sure what kind it is? Bug Guide and iNaturalist are great resources!

Further reading

Darien Becker
Environmental Educator, WEC