If you look closely at bare twigs and stems in the winter, you may come across a hard papier-mâché-like blob approximately an inch across. This is a praying mantis ootheca, a type of egg mass laid by a variety of species, including mollusks and cockroaches, as well as mantises. The word “ootheca” is a combination of the Greek words “oon” meaning egg, and “theca” meaning cover or container. The ootheca material is produced from a pair of accessory reproductive glands on the female mantid and begins as a light foam before hardening to form a protective case. This covering will guard the eggs inside from parasites, predators and weather. This protection is vital, since after the eggs are laid, adults provide no further care or protection. Eggs overwinter in the ootheca, hatching when the temperature warms in the spring.

A hard papier-mâché-like praying mantis egg mass.

Ootheca attached to dried stems at the edge of an abandoned cranberry bog in Plymouth. 

While there are species of praying mantis native to North America, they are more common in southern states. In New England, the most commonly encountered species are the Chinese mantis (Tenodera sinensis) and the European mantis (Mantis religiosa). Based on the size and shape of this ootheca, this particular egg mass is likely from the Chinese mantis. Chinese mantis oothecae (plural for “ootheca”) are rounder, with an almost smooshed or melted look, while European oothecae tend to be more elongate with regular, defined layers. For a photographic comparison of oothecae produced by various mantid species, check out this BugGuide page. The Chinese mantis is native to Asia, but was introduced to the United States in the late 1800s. It is now common throughout the country and is the most widespread and abundant mantis species in temperate zones.

Chinese mantises produce roundish oothecae.

Chinese mantis oothecae tend to have a smooshed or melted appearance compared to European mantis oothecae.