This is from PetPlanet.co.uk:
Bites and stings
Insect stings are another potential summer hazard for dogs, particularly for puppies and playful ones who can't resist trying to make friends with bees flying from flower to flower, or who gobble up any insect they find on the ground. Bites and stings tend to be on the head and mouth area, and if your pet is stung near its mouth or in its throat it may swell and restrict breathing. Some animals may also be allergic to bee and wasp stings and quickly collapse. If you think your dog may have been stung in the mouth area, check that the airway is clear and take it to the vet's surgery immediately.
Bee stings are acid. Remove the sting and bathe the area in bicarbonate of soda.
Wasp stings are alkali, and the sting is not left in the skin. Bathe the area in vinegar as the sting is alkaline.
If your dog is one of those who likes to romp in long grass, or your walks take you through heathland, there is just a small chance that it could disturb a basking adder, with serious consequences. If you suspect that your dog may have been bitten by an adder, seek veterinary help immediately.
Hope this helps,