Looks like you are the proud parent of the next generation of praying mantises in your garden. That is an egg case I believe.

should I remove it??

Praying mantis is a beneficial insect, although they have no problem killing and eating the butterflies. They are an interesting addition to the garden, and I do not think anyone ever explained why some mature brown and some mature green. When I was a kid we were told it was a crime to kill one. Why such a story would come is a mystery, but nobody questioned the truth of it.

I wouldn't remove it - Those mantises will eat all the bugs they can find (including themselves).

I don't know why this is, but I've noticed that mantises seem to like spireas.

here is the key for you:

momma used the branch to STICK the egg sack to ...

it is not harmful to the plant ...

the only reason to remove it.. is to put it in an aquarium to watch it all happen ... but then.. you are exposing the babes ...

ignore it ... check it every day.. later in spring ...

ken

Many gardeners pay money for these!

Here is a link that might be useful: On Sale at Amazon.com

The reason that there are green, brown, big and small mantids is because there are many, many different species.

Don't remove it to bring inside. Hatching will occur prematurely, forcing the babies to hunt down each other for food.

I don't like them. I find them in my flower garden where they are happy to snatch butterflies all day long. Even if moved to the veggie area, they'll move back within a few minutes.

I won't kill them, but will send them to work with my husband.

They eat honeybees as well. If it were me I'd leave it but just so you are aware. Once watched one for about an hour at the Huntington Garden in So Cal - it was sitting on a rose, calmly and deliberately munching away at a honeybee. People kept coming up to me to find out what I was observing so intently, thinking it was the gaudy pink rose. When they saw what it was, most left in disgust!