Cicadas do not bite and are not poisonous and are actually a part of the regular diet for people in many countries, but they could make your Fido sick.
Dr. Sheri Bakerian with Fredericksburg Animal Hospital says if a pet eats one or two, it's probably okay. It's when they overindulge that there could be a problem. If they do start to throw up, call your vet immediately. You will likely be told to comfort them and withhold all food for up to 12 hours. Once they do feel better, you'll probably be told to restart them on a bland diet.