These guys can do a number on vegetables. I had a ton of them last year and they sucked the life out of the tomato vines and ruined the fruit to boot.

The nymphs seem to love prickly pears and can destroy them also.

The best thing to do is to keep your place as clean as you can, especially in winter. I chopped out all the long weeds and grass along the fencelines etc and kept everything trimmed up and clean over winter, and they didn't come back this year.