Generally, I would think too many would be what the insect population/food supply would not support. The one thing I've heard about praying mantis though is that they can eat humming birds, so for them too many would also include them taking a toll on the hummers.

OMG they eat hummingbirds? I have a lot of them by my house, that would be horrible! How they heck do they manage to kill hummingbirds?? JEEZ! For now I'll let them be, but if they stick around too long, I'll gather them up and release them elsewhere.

You can put some in a box and bring them to me at the swap.. I would be thrilled! I haven't seen one in my yard for awhile. If you see any egg cases that would be even better. I found an egg case once in my yard and put it in a jar to watch the little ones hatch. When they did I took them outside to a plant that had aphids. They immediately started gobbling them up even though the little mantis babies had just hatched.

My M-i-L saw a very large one grab a hummingbird once, but I think it is pretty rare.

Here is a link that might be useful: Praying mantis egg case photos ...

I'll be on the look out over the next few days, I looked for them when I got in and didn't see one. I'm sure they'll be back, I'm thinking it's bc I'm on a greenbelt bc I get a lot of insect activity. Egg cases? Ick lol

They do stalk hummers. Last summer I had one crawl up on my feeder to lay in wait. I am glad to have them to kill bad bugs but
not my hummers.

oooh, lucky you, Pink ! I'm with Roselee... I think it's a rare thing that they would catch a hummer. They are an insect that you will want in your yard. But if not, bring them to the swap and we'll take them!

It's only the very large imported (now invasive) Chinese mantid that would be able to snatch a hummingbird. Unfortunately, they are becoming more common in our gardens, taking over the native species' environment.

I remove mantids of any kind from my yard and garden. They do nothing to control aphids, whitefly, scale, and spidermites but sure do a number on my bees and butterflies!

Over many years I've observed these crafty little devils avoiding my veggie areas, where they could actually do some good, in order to stalk my annual and perennial beds where the pollinators hang out in droves. I've even moved them from one location to another only to watch them fly back immediately, lol.

About 60 years ago I saw a mantis kill a hummer. I was playing jacks on the front porch and was horrified.