h1. Nesting Bluebird Info Wren Guard - apply after first egg has been laid. - made from cardboard. - three sided. - extends outward 3 to 3.5 inches from the nest box. - extends down to the bottom edge of hole. Change Nest - 6 to 7 days after young have hatched. - this is more important for the 2nd and 3rd nestings, during the warmer, summer period. - may not see any indications of blowfly existence during the spring nesting. - make new nest from dried grasses. - lawn grass can be used, provided that it has been dried sufficiently. - green grass will generate heat as it dries or decomposes. - can use lawn clippings. - spread green grass out on table or floor to dry and then store in a plastic bag until needed. -