Leah:

You are correct, this is a praying mantis egg case. The orientation of the egg case is ok, the female choses the location and the orientation. I have included some information about egg cases below so you can watch over it if you wish. Let me know if you have any additional questions.

Rich

Praying mantis egg cases

The adult female mantis lays her massive egg case, known as an ootheca, on twigs, stems, rocks, or even the sides of buildings or fence posts. Ootheca comes from the Greek word "oo," meaning egg and the Latin word, "theca," meaning a cover or container.

For the female, the location requires only that it will hold her body weight and is somewhat vertical.

After laying, the ootheca quickly hardens in preparation for a winter slumber, and the mother will die shortly after. These egg cases, which we tend to find in fall and winter, are light brown, about 1.5 inches wide and look like foam insulation. Within each foam-like ootheca are dozens or hundreds mantis eggs that can survive the perils of winter because of their foamy insulation.

If they must be removed from a wall, transfer them to a sheltered place. Never put an egg case on the ground; the eggs inside will be consumed by ants.

Hatching

When springlike temperatures greet us, we can expect some 100 to 200 praying mantids to hatch or emerge from each egg case, starting their journey to find insects, which may include their brothers and sisters. Most of the mantises that hatch from an egg case will die from starvation or cannibalism. They are territorial and by the end of the summer, usually, only one adult remains.

Information compiled from:

-University of California., Agriculture and Natural Resources

-Cooperative Extension System, University of Illinois Extension