Heterozygotes show venation abnormalities with tiny free veins usually in the third posterior cell and occasionally in the second in about 50% of males and 90% of females. Less often, extra veinlets project from posterior crossvein. Homozygotes have bizzare networks of wing veins. Wings of freshly emerged adults inflated with hemolymph, producing large blister in middle of one or both wings just posterior to the anterior crossvein. Blisters cover one-fourth to one-half of total wing area. Lymph later dries, leaving wing vesiculated and curled upward. More pronounced in females. Flight restricted. bs^cy/bs² females are like weak bs^cy and males like bs². RK1.