While I'm quoting Jim Henley (who is recovering nicely from that weird library thing from a few months back) I'll happily point to this piece on the nascent "weapons of (some) destruction" debate... whether chemical and biological weapons really count as weapons of mass destruction.
Personally, I argue for a little nuance and complexity here. (Surprise.) There's no doubt that some chemicals and biological agents can theoretically be as deadly as an equivalent-sized nuke, but that isn't usually what we're talking about, and those are under best-case-scenario conditions. (Well, for the attacker.) Jim Henley's example of a fuel-air bomb as a type of WMD illustrates how illusory this definition can be, and brings up a very good point- what happens when "conventional" explosive weapons are just as effective? Dead is dead, after all.
It should probably come down to which chemical, and which bug. Some really should count as WMDs, and some shouldn't. Doesn't mean that banning them from the battlefield isn't a good idea anyway, but conflating them with nukes gets you in all sorts of trouble, especially once the whole argument gets broken down and starts looking somewhat suspicious. It's not necessary (the treaties that ban them don't worry about "WMDs", after all), so why bother?
(Well, unless you're pushing a sham justification for a war, that is. But that's a different story.)