[5] Pregnant females look for host plants like Diplacus aurantiacus that are close to nectar sources when they lay their eggs.

[7] After moving to a darker and more secluded site, larvae enter diapause, emerging between January and March with pupation usually beginning in April.

[9] Due to a larval diet rich in catalpol, this butterfly has developed a strategy of unpalatability to deter avian predation.

Its habitat is bounded to the west by the Pacific Ocean and it extends east past the Rocky Mountains into Montana, Wyoming, Colorado and New Mexico.

[2] The butterfly's habitat encompasses a large variety of environments, including sagebrush flats, desert hills, prairies, open forests and alpine tundra.

[8] Before they enter diapause, the larvae leave the food plant to seek better dormancy sites such as under the bark of dead branches, in the hollow stems of dried weeds and in rock crevices.

[3] In addition, virgin females, the most desirable mates for male butterflies, are most often found near larval host plants.

[16] To start courtship, the male arrives in the vicinity of a fertilizable female, who quickly moves to the ground or to vegetation.

Variable checkerspot eggs are always distributed around good larval food sources, regardless of the level of male harassment at those sites.

Thus, after males produce the spermatophore, they pass an additional gland secretion that spills out of the female's copulatory opening, forming a mating plug that hardens within a few hours of copulation.

[5] During the flight season, large groups of variable checkerspot butterflies can be found across western North America.

Individual butterflies are capable of recognizing suitable areas rich in larval food plants and do not usually linger in other parts of the landscape.

[8] The principal food source for variable checkerspot larvae are the leaves of the flowering subshrub Diplacus aurantiacus that also usually serve as its host plant.

D. aurantiacus contains large amounts of a leaf phenolic resin, which helps resist water loss during drought.

[23] To maximize their own nutritional benefits, larvae selectively eat leaves with the highest available nitrogen:resin ratio.

[25] In contrast to the herbivorous diet of the larva, the adult variable checkerspot's main food source is the nectar it obtains from flowers.

In Jasper Ridge Biological Preserve in California, an extremely well studied site, the nectar source most frequently used by adult butterflies is Eriodictyon californicum.

[6] The diet of the adult butterfly has a large impact on the choice of D. aurantiacus as the oviposition site and larval host of the variable checkerspot.

Populations of the variable checkerspot, like most lepidopterans, are usually scarcely distributed and thus direct observation of avian predation on butterflies is rare.

Indeed, the pressure exerted on the variable checkerspot by visually hunting avian predators may play an important role in the evolution of its wing coloration and pattern.

[12] The variable checkerspot, like many other butterflies, has developed a defense strategy of unpalatability to birds as a means of resisting predation.

In a controlled experiment, would-be avian predators often exhibit head-shaking and beak-wiping behavior after killing a variable checkerspot, characteristic of tasting unpalatable prey.

The unpleasant taste of the butterfly is likely due to the presence of iridoid glycoside compounds in the scrophulariaceous plants that make up the majority of its larval diet.

[10] Because they are essential for the larvae to develop an unpalatable taste to birds, iridoids act as larval feeding stimulants.