In the temperature sensitive combination Egfr^top-CA/Egfr^f7 the pleura expands at the expense of the sternites and tergites.

Homozygotes have mutant egg chambers. Posterior follicle cells of Egfr^top-CA/Egfr^t1 transheterozygotes have an abnormal shape and behaviour.

Homozygotes usually die during postembryonic development. 25-49% of Egfr^top-CA/Egfr^f7 flies survive to adulthood (FBrf0049928). The anterior dorsal, posterior dorsal, ventral and spiracular histoblast nests contain fewer cells than in wild-type pupae 6 hours after pupariation. The dorsal histoblast nests remain separate 24 hours after pupariation, in contrast to wild-type where they are fused. The histoblast nests in the anterior segments are less abnormal than those in posterior segments. Adults sometimes have holes in the abdominal cuticle and lack spiracles in the abdominal segments. In less severely affected adults chaetae appear abnormal and the distribution of hairs on the tergite, sternite and pleura is irregular and sparse. The thickness of the cuticle is reduced and spiracles are abnormal.

Homozygous adult semi-viable. In trans to Egfr^t1, Egfr^top-CA and Egfr^top-EE38 show unusually weak eye defects.

Homozygotes die during postembryonic development and hemizygotes are pupal lethal. The few homozygous adult escapers survive poorly.