If the sting remains in the affected part do not try to pull it out or squeeze the affected area as this will only serve to inject more venom into the wound.
Instead try to scrape it out with the fingernails.
Immediately wash with soap and water. Take an acute homeopathic remedy after quickly consulting this software. If appropriate to the individual (and watch their reaction) apply an ice-pack.
If you suspect the bite or sting could be strongly venomous get to the nearest hospital quickly!