We have had these bugs nesting near our patio in a hanging "chime" for a few years now, that has horizontal metal tubes. They plug up the middle of the tube with grasses and close down the entrance so they can squeeze in- and plug it up completely in the winter. They seem to be a solitary insect- 1 bug per tube entrance- although we do have a few living in this chime. I too have seen them resting on trees- and vertical plants in the garden- and I believe the males are much smaller- shorter, thicker and more bronze/sheen black colored- who knew they were hard to find- maybe I should bottle one up and make a call next time I think I see what I think is a male- they do not appear to live long- I doubt I will see one again this year- although momma can be seen tending the nest early in the cooler morning temps in the hot weather. I believe they live longer than one year- as it sure seems to be the same creature we see every year for the last few years. They are frightening to witness- but we have never had any trouble with these bugs- they generally keep to themselves and have never shown any aggression- and actually seem to prefer privacy and solitude. Bonus that they like grubs! I was concerned they might be harming trees. I hope you can put your concerns to rest soon and maybe even appreciate them for their fearsomely odd appearance-

I think that it's a good rule to try to ID the crawly things you find in your garden BEFORE you begin squishing. There are so many helpful little guys out there. Almost anything can be identified right here, with a reasonably decent image. Your picture was great, by the way!

The picture is not of a beetle at all, but one of the large group of insects we refer to as 'true bugs'. It's is a nymph. I have no idea what you might have without a picture to go by. But I can tell you one thing...if they were all going after a dead worm, then they are probably good guys. There are thousands of species of beetles and other insects that have the job of cleaning up the dead stuff. Without them, we'd be surrounded by mountains of dead critters of all kinds. These are the beneficial scavengers. IF, however, they had come upon a live worm and (as a hoard), killed it and devoured it, that act would put them in the predator stage. I doubt that this is the case.

Looks like one of the instars of Assassin Bug ( Reduviidae family). They feed off of other insects and don't damage plants for the most part but have been known to "sting"/stab people if threatened. Generally considered a good guy when it comes to garden pest controls Dave.