Fig. 9. Lethal phenotypes caused by GAL4-EcR overexpression are similar to EcR mutant phenotypes at the onset of metamorphosis. Control w¹¹¹⁸ and homozygous hs-GAL4-EcR third instar larvae were subjected to two sequential heat treatments for 40 minutes at 38°C, separated by a 4 hour recovery period. (A) 98% of the control w¹¹¹⁸ animals form tanned barrel-shaped pupal cases under these conditions. 62% of heat-treated hs-GAL4-EcR animals arrest their development as non-pupariating third instar larvae (B) and 28% form elongated untanned prepupae (C). The remaining 10% form partially tanned and misshapen pupal cases (data not shown) (n=120 for each line).