I believe older chickens have mites in coop. they avoid going intill very last minute.... Plus they constantly go into younger Barr Rocks coop... thy have so many broken jagged feathers, and underweight etc.... I am willing to spend money on a good one. The older propane Ortho brand one, one I had from years ago is clogged and rusted out. Plus can be used in asemet with so many spiders.... Believe some newbie on here recommened Cedarcide and Tri jet one..... anyone with comments and used one or other????