irEx274 [ZK177 + unc-119::CFP + rol-6(su1006)]. Maintain by picking Rollers. Strain throws Rollers (expressing unc-119::CFP), dead eggs, and developmentally-arrrested L1s. Roller is often weak or not apparent. A greater proportion of tbx-35(tm1789) embryos will hatch as inviable L1s at 15C as compared with 20C or 25C.