Answer: Harlequin bugs are primarily atttracted to cole crops but will also eat tomatoes, so I am a little surprised they attacked your cleome first. If they appear again this year, you might wish to contact your county extension for a definite identification of the pest and their suggested controls for it.
Since the problem was severe, whatever the pest was, there are several things you can do. First, clean up the garden as best you can to eliminate overwintering pests. (Harlequins overwinter as adults.) Also remove neighboring weeds, particularly any wild mustard (harlequin bugs like it), in the vicinity. Next, keep an eye out in very early spring for any harlequin bug adults. Catch them if you can, to try to stop the egg laying stage. Next, watch on the undersides of leaves for clusters of eggs and remove any you find. Then, should the population continue to increase and damage become noticeable, you could use carbaryl (Sevin) according to the label instructions to control harlequin bugs.
Q&A Library Searching Tips