Ace^j40/Ace^j19 second and third instar larvae which have been raised at 18^oC are no more susceptible to heat-induced paralysis when exposed to 38^oC than control larvae, and are if anything, less adversely affected.

Ace^j40/Ace^j19 adults which have been raised at 18^oC show a slight defects in phototactic behaviour when tested at 18^oC. The defects in phototaxis increase if the flies are subjected to 29^oC.

Ace^j40/Ace^j19 adults which have been raised at 18^oC but subjected to a heat pulse during pupal development show severely defective phototaxis, while heat treatment during larval development results in only a slight decrement in phototaxis in the resulting adults.