Mud daubers and pollen wasps construct mud cells in sheltered places. Brown widows are often preyed on by mud daubers and sometimes by digger wasps. Like most other wasps, mud daubers are predators. Juveniles are frequently preyed upon by mud daubers. Mud daubers prefer particular kinds and sizes of spiders for their larders. Blue mud daubers are the main predator of the black and brown widow spiders. To mark cards faster the players usually use special markers called "daubers". Mud daubers are not normally aggressive, but can become belligerent when threatened. Mud daubers belong to different families and are variable in appearance. Here are some characteristics of mud daubers of the genus "Sceliphron". They were later referred to as JD Wilkes and the Dirt Daubers.