• Monarchs are a sexually dimorphic species, meaning that the females look different from the males (10).

• The males do not need to emit pheromones due to this dimorphism, rather they use a coercive mating system (10). 

~ Summer populations: use less aggressive mating tactics because the scent glands decrease the females' struggle.

~ Overwintering Populations: do not use scent glands to calm the females, rather the male utilizes his claspers on the female's abdomen to restrain the female prior to copulation (10). 

• Males: have smaller veins, 2 black spots on their back wings, and claspers on their abdomen which are utilized to hold the female before copulation(19).

The two black spots are scent glands, which produce a "flowerlike scent" to calm frantic females before copulation after capture. In addition, brush like structures, called anal hair pencils, are used to spread the scent over the female(10). 

• Females: have thicker veins with no claspers on their abdomen (19).