What’s the difference between a bee sting and wasp sting? I know bee stingers are barbed and stay in, but what about the poison?

For a bee, a sting is all or nothing; the bee loses its stinger and injects a relatively large volume of venom — typically about 50 micrograms.

A wasp, which retains its stinger, injects from 2 to 15 micrograms — but it can do it many times.

Chemically, the venoms are quite different, though the effects are similar. You can be allergic to one type of sting and not the other. Both types are complicated mixtures of chemicals, but here’s a rough idea of what’s in them:

Wasp venoms have enzymes that break down cell membranes, as well as neurotransmitters like acetylcholine and serotonin, which get nerves firing. They also have substances that trigger the release of histamine, producing an intense allergy-like reaction similar to getting hives.

Bee stings are more than 50 percent melittin, a powerful toxin that works by stimulating an enzyme involved in inflammation. Like wasp venoms, a lot of what it does involves making the body release histamine and produce a hives-like reaction.

Both venoms contain hyaluronidase, which breaks down the barrier between cells, helping the venom to spread. Wasps and bees also both signal others of their kind after they sting, so it’s a good idea to get far away after the first sting.

Since the venoms are injected, most folk remedies have little basis in science, but anything that either cools or numbs the wound and takes the victim’s mind off the pain will help.

Bee stingers should be removed, since the venom sac remains attached when the bee flies off and can continue injecting venom for some time. Antihistamines may help a bit, but in case of a severe allergic reaction, call 911 immediately.

Ask Dr. Knowledge is written by Northeastern University physicist John Swain. E-mail questions to drknowledge@globe.com or write to Dr. Knowledge, c/o The Boston Globe, PO Box 55819, Boston, MA 02205-5819.

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