DISCUSSION
The results of these studies are clear: using a negative
phototactic behavioral assay, scorpion locomotor behavior is
highest at UV irradiance levels that correspond to sunset.
Adding additional indicators, such as the distribution of
instantaneous velocities and the number of legitimate trials by
light treatment, suggests that the UV response threshold
detected by this assay is between the 0.15 mW/cm2 and
0.01 mW/cm2 light responses. Pooling across all light treatments,
we also found a difference in the activity of males and females,
which is to be expected since these trials were conducted at the
end of the mating season when males are more active on the
surface and tracking females (Bradley 1988).
This study demonstrates that scorpions respond differently