Expression of HC2.hs using heat shock only induces ectopic wing veins when it is overexpressed between day 5 and 6 after egg deposition. The phenocritical period is restricted to the prepupal and early pupal stage, starting approximately at the larval-prepupal transition. Bifurcation of wing vein L2 is sometimes seen. Overexpression of HC2.hs during the mid- to late-third instar does not result in ectopic vein formation. Co-expression of Hhs.PM and HC2.hs results in a synergistic phenotype with strong induction of ectopic wing veins.
Heat induced expression causes no or negligible bristle duplications or socket to shaft transformations. Expression does cause a specific net-like wing venation is observed on the wings.