Gerbera are prone to several insects such as thrips, whitefly, aphids and spider mites none of which fit the description of your tiny black bug. There is a tiny black beetle called flea beetle that jumps like a flea when disturbed . They chew small round holes on vegetable and some flowers.

Recipe for repellent

Nothing is more frustrating than putting all that time and effort into planting only to find something had a great feast at your expense. Sources tell me that repellents containing pure capsaicin (see Capsaicin article)will repel squirrels, rabbits & deer. For a nice piece of change, there are some commercial products out there that specifically claim to be rabbit and squirrel deterrents. You can make your own version in your kitchen by mixing 1/2 cup finely chopped Jalepenos or Habanero peppers w.1/2 gal of water. Boil 20 min. do not inhale vapors as they can burn, strain, and use as spray. Wear gloves when handling peppers. You can also try ground cayenne peppers. Re-apply once a week or after heavy rain. Hopefully, this will keep those buggers at bay.

Rabbits have been very prolific this season and when hungry will eat just about anything; a plant that may be recommended as rabbit proof may turn out to get eaten anyway. Here are a few perennials that Bugs bunny does not like: vinca, yucca, columbine, spurge, daylilly, daffodils, solomon seal and sedum. Not a very extensive list. There are some things you can do. Fencing seems to be the most effective-bury 6 inches of a 2 and a half foot chicken wire fence underground.
There are several repellants which should be used before damage occurs or the animal has tasted the plant. Thiram a fungicide is recommended as an animal repellant. Deer Away & Hinder seem to get good results for both deer and rabbits. People have tried baby powder, blood meal and lion feces with mixed results. They do not weather well and need to be re-applied on foliage every 5 days or after any rain or dew. Another interesting one is coffee grounds mixed in the soil. Coffee is high in nitrogen and acid, moderation is a good idea in areas with low ph. If all else fails a dog.

It could be a type of ground squirrel or chipmunk. Chipmunks are not protected in Illinois and therefore you can trap them. Live trapping with commercial or homemade boxes can reduce their numbers. Once caught they need to be released at least one mile away from the area. Rat sized snap trap also work, but they will kill them. Use peanut butter, nut meats, sunflower seeds or rolled oats as bait and place in the area where they seem to be off nuisance.