From The Collaborative International Dictionary of English v.0.48 :
mud-dauber \mud"-daub`er\, mud dauber \mud" daub`er\, n.
Sphegidae+({Sphecidae">A wasp of the family Sphegidae ({Sphecidae) which builds a
nest of mud and stores insects and spiders in it; a
digger-wasp.
[PJC] mud-crab