Imprecise excision of the P{lArB} element, with one breakpoint in the element and the other downstream of the original insertion site, in intron 3 of Oamb.
Homozygous adults have normal gross external morphology. Homozygous females produce very few or no eggs; no females produce more than 10 eggs and the average number of progeny from females is 0.9 +/- 0.3.