Colorful, but invasive: the Bagrada bug.
Question: I would like to know what this bug is please. I have spent hours researching it. Thank you!
Answer: Thanks for the picture! You have the nymph (immature) of a stink bug called a Bagrada bug. In the U.S. this species was first found in California and Arizona in 2008; far away from its native home in parts of Africa, Asia, and Europe. These bugs feed primarily on plants in the mustard family, including cabbage, broccoli, and Brussels sprouts. The UC Davis IPM program has more information about this pest in an online fact sheet.
– Scott Berg, M.S.