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The Palos Verdes Blue is a small blue and silver butterfly only found in the Palos Verdes Peninsula in Southwest Los Angeles County. It is a subspecies of the silvery blue and was discovered in the early 1970s. The Palos Verdes blue depends on two host plants, locoweed (Astragalus lonchus) and common deerweed (Lotus scoparius).

At the end of the winter, the Palos Verdes Blue butterflies emerge from diapause and fly about their habitat. Usually, males emerge before females. Once they are sexually mature, the males search for and mate with females. The mated females then start searching for sites to lay their eggs. Females generally prefer deerweed plants called lotus scoparius. The larvae eclose three to five days later and start feeding upon the flower and leaf buds.

As the larvae get larger, a specie of ants (carpenter ants) protects the larvae against predators and parasites. In return, the Palos Verdes Blue larvae provides the carpenter ants with amino acids and sugars. The butterfly larvae are taking advantage of the fact that the ants believe they are actually ants larvae.

After three to four weeks the larvae mature and go into a stage that consists in looking for a pupation site. The carpenter ants follow them there, continuing their mutually benefiting relationship. Then the larvae enter diapause as they mature and the cycle starts again.

When exploring this website you will learn that the butterfly was thought to be extinct but reappeared years later. Its population is so small that it is considered the world’s rarest butterfly. Because the Palos Verdes Blue only feeds on two types of plants, they are extremely sensitive to habitat changes and human impacts.


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