Often associated with In(3R)P. Useful as a balancer for 3L. Allows only about 0.02% crossing over between ru and st. Balancers contain recessive lethals or Me. Balancers for all of chromosome 3 made by combining In(3L)P with In(3R)P or In(3R)C. Found in many wild populations (e.g., Warters, 1944, Texas Univ. Publ. 4445: 129-174; Oshima and Watanabe, 1965, D. I. S. 40: 88; Stalker, 1976, Genetics 82: 323-47; Mettler, Voelker and Mukai, 1977, Genetics 87: 169-76; Knibb, 1982, Genetics 58: 213-21).