During the northern remigration of monarchs in the spring, the time-compensated sun compass uses the same substrates as used in the fall.[1] However, the mechanistic differences in these substrates that allows for a switch in the directionality of the compass is still unknown. RNA-sequencing differences found between the fall and spring butterflies is one avenue of research that could locate the mechanism responsible for the recalibration, which may utilize a temperature sensor to start the switch.[2]