It is named after its cobalt-blue exoskeleton, which makes it easy to spot and distinguish, and its tendency to feed off milkweed plants.

By storing them in pronotal and elytra glands, they can utilize these toxins to their advantage and evolutionary benefit.

After the mating has occurred, males tend to stay mounted on the female's back for an average of 1.7 hours.

This postcopulatory behavior has been attributed to increase the male's chance of producing his offspring with his paternal genes.

[3] C. cobaltinus is similar to click beetles in being able to launch themselves a couple times the length of their body.

Sequencing studies found a single mutation in the alpha-subunit of the Na+/K+-ATPase proteins that seem to confer cardenolide-resistance.

The mutation (found at amino acid position 122) is a switch from asparagine to histidine which has made it so that the toxic molecules can no longer bind and inhibit the ATPase protein.

[7] Further, C. cobaltinus has evolved to use these toxic molecules for its own benefit and defense against predators (See protective behavior section).

C.cobaltinus beetles have established defensive behaviors in which they release toxic secretions from their pronotal and elytral glands.

These cardenolides are the same toxins found in the Asclepias and Apocynum plants that make up the beetles' primary source of food.

Studies found that C.cobaltinus (and C.auratus) have developed mechanisms to sequester these cardenolides in their pronotal and elytral glands; there, these molecules are stored to be released in the case of danger.

But, if a predator threatens the beetle's survival, it can release small secretions that contain a high concentration of the cardenolides.

[8] C. cobaltinus beetles take part in polygamous mating which allows the species to increase genetic diversity and propagations.

The male beetle rides on the female's back for a period lasting no longer than 20 minutes.

This period lasts for an average of 1.7 hours and has been theorized to occur for the male beetle's evolutionary benefit.

This period of postcopulatory riding can also mutually benefit both female and male beetles as it offers some protection against predators.

Studies found that females that mate with multiple partners resultingly have an increase in the number of daily eggs produced.

[9] C. cobaltinus and C. auratus share a strip of land in the state of Washington in which both species are heavily present.

Therefore, many of these hybrids are easy to identify since they have intermediate color and antennal morphology to C. auratus and C. cobaltinus.

C. cobaltinus male beetles have been shown to respond to cuticular hydrocarbon (CHC) profiles around them.

Male beetles were shown to have the ability to identify between these different species CHC profiles.

On the other hand, C. cobaltinus females' F1 hybrid offspring production was proportional to heterospecific mating frequency.

Hybrid zone males also have the ability to detect conspecific and heterospecific females based on hydrocarbons.

Examining the diet of these species show that C. auratus ate Apocynum cannabinum while avoiding Asclepias speciosa and As.

[12] Adults emerge in early summer and stay on milkweed plants in patches for approximately six weeks.

Females are highly polyandrous; males engage in extended periods of post-copulatory mate guarding.

[3] C. cobaltinus resides in High Plains which reach from British Columbia to the south through Washington, Idaho, Montana, Oregon, California, Nevada, Utah, and Colorado to Arizona and New Mexico.

These two species form a 25-km wide hybrid zone in the Yakima River valley of Washington state.

Additionally, the beetles found there have intermediate physical characteristics that would indicate an introgression between C. cobaltinus and C. auratus.