Expression of Abd-B^m.hs using heat shock during the late cellular blastoderm stage results in ectopic filzkorper on the dorsal surface of the anterior abdominal segments in first instar larvae. These ectopic filzkorper are usually accompanied by perispiracular hairs. The denticle belts of abdominal segments 2 through to 8 remain normal in size and shape, while the A1 denticle belt is often reduced in size. Ectopic structures resembling ventral pits (which are normally found only in thoracic segments) are often seen in ventro-lateral positions in abdominal segments. Head involution is inhibited and a mixture of thoracic and abdominal denticle hairs are occasionally seen in cephalic segments. The first thoracic denticle belt is often reduced in size and the T1 beard is often reduced or missing. Expression of Abd-B^m.hs using heat shock during the first 24 hours of the third larval instar stage often results in transformation of distal antennal structures into distal leg structures. The arista is transformed into tarsal leg and tarsal claws occasionally develop in the distalmost regions of the transformed leg tissue. Part of the third antennal segment is sometimes transformed towards more proximal leg tissue, producing leg bristles. Many of these animals do not eclose from the pupal case. Expression of Abd-B^m.hs using heat shock for 30 minutes during the second day of the third larval instar stage results in late larval or early pupal lethality in most cases.