Tiny little bugs on a Jalapeno seedling
Yesterday I found some very tiny (have to get real close to see they're bugs) little brown/light brown bugs (100's of them) on one of my Jalapeno Early Organic seedlings. It has 5/6 leaves & is about 3-4 inches tall. I got rid of most of the bugs temporarily by using canned air, which froze half a leaf on the plant. :-\ Then, I rushed home after work and checked all my other seedlings and none of them had the bugs. The one that did, I brought to work about a week ago. I sprayed it today with GardenSafe Fruit & Vvegetable Pest spray, even though it didn't have the bugs anymore (??).
My questions are this:
What are they?
Did they possibly come from another plant in the office at work?
If not, do I need to be worried about them being on other plants (maybe they're in the soil mix, etc.)?
Are they harmful to the plant?
Also, what's a definite method of killing them, if they are harmful to my plants?
Any & all help appreciated.
Peace - Steve