You can walk into a garden center, buy a praying mantis egg case off the shelf, and set a hummingbird trap in your own backyard without ever knowing it.
The egg cases sold as natural pest control are almost always Chinese mantis, sometimes European mantis. Both were brought to the US over a century ago, the Chinese one by accident on a shipment of plants in 1896, and both have spread everywhere since. They get marketed as an organic way to handle pests. The pitch hides a few ugly details.
A Chinese mantis grows to four or five inches, more than twice the size of our native Carolina mantis. It's an ambush predator that sits on a flower and grabs whatever lands, which means it eats the exact things you planted the flower to attract. Bumblebees. Butterflies, monarchs included. At one wildlife garden in Brooklyn, staff kept finding little piles of discarded monarch wings under the mantises' favorite perches.
It gets worse. These things are big enough to take a hummingbird. Scientists have documented well over a hundred cases of mantises catching and killing small birds, most of them hummingbirds, snatched right at flowers and feeders. The big imported mantis will also hunt down and eat the smaller native Carolina mantis, so buying one actively shoves out the local species.
So if you want the pest control, plant for it instead. A yard full of native flowers pulls in the wasps, birds, and native mantis that handle pests without ambushing your hummingbirds.
And if you find a fat, beige, ping-pong-ball-sized egg case on a twig this winter, that's the imported one. You're allowed to clip it.