By Linda Ray
It is still winter here in the last days of February, and a lovely, soft snowstorm is happening outside my window. In a month’s time, spring life will start erupting, but, right now, overwintering insects remain protected in their specific survival modes. In keeping with the theme of insect overwintering techniques, let’s take a look at how some insects endure the winter as eggs. That’s right—they survive not in a chrysalis, cocoon, or underground (like Japanese beetles), nor by migrating or hibernating as adults (such as ladybird beetles), but as tiny, seemingly defenseless eggs. Or are they truly defenseless?
One recognizable insect whose eggs make it through Maine’s cold winters is the praying mantis. There are eight families in the order Mantodea and approximately 2,000 species worldwide, with two species found in New England. Mantids are hemimetabolous insects, meaning their life cycle consists of three stages: egg, nymph, and adult. In New England, adult mantids live approximately six to eight months and do not survive the cold.
In the late summer or fall, a female mantid, such as the mantis religiosa or European mantis (of the family Mantidae), lays her eggs within a gooey mass called an ootheca (egg case). She deposits the ootheca on rocks, sturdy stems like goldenrod, barn walls, or sheds. The term ootheca translates to “a place to keep” and can contain hundreds of eggs, depending on the species. Initially, the ootheca appears as a frothy, foamy liquid which hardens over the following days, forming a resilient, protective, and insulating enclosure for the eggs—one that blends well with its surroundings. Before she succumbs to the cold, the female mantis may deposit multiple egg cases. Despite being exposed to wind, snow, ice, and freezing temperatures, the mantis eggs endure.
Many oothecae remain strong and secure throughout the winter until the eggs hatch as nymphs in the spring, ensuring another thriving generation. Several other insects, such as cockroaches and corn worms, also survive the winter as eggs, though they may not be as glamorous as mantids. While mantids have a reputation as the T. rex of the insect world, mantid mothers use those same predatory skills to protect their oothecae—right up until the mama perishes from the cold.
Sources:
Marshall, Stephen A., 2013, Insects, Their Natural History and Diversity, Firefly Books Ltd., Buffalo, NY
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