Imprecise excision of the P{lacW} element, removing the 3' end of the element and approximately 12.3kb of genomic sequence.
Lethality occurs during the third larval instar. The early ecdysone puffs 50CD, 74E, 75B and the late puffs 29F, 46F, 62E, 71CE, 78C, 82F, 85D, 93D and 98E are not present in mutant larvae. The intermolt puffs 34A, 25AB and 68C do not disappear in these mutants.