Centipedes do spam the heck out of quagmire.
Quite a pain in the butt, but something you'll have to learn to deal with when leveling at that particular map.
My main way of handling it is to clear an entire area of the map of centipedes to create a "safe zone." This safe zone will be what you try to get to if you need to teleport to recuperate your health/mana/give pet crap to hold.
For some reason, if you keep killing in an area, the monsters will spawn into another area of the map. I recommend the first two cubby holes you can find on the right hand side of the map.
The downside of this method means you've effectively made it more difficult to kill in another area.
Of course, if you have the patience of an ox, you can always polymorph all the bugs with a hylozoist clip.