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38 <br />As the butterfly is known to be able to fly significant distances (up to a mile), these habitat <br />requirements can be somewhat spread out and still support a silverspot population. <br />The silverspot butterflies produce just one generation each year. The four stages in a butterfly’s <br />life cycle include egg, larva (i.e., caterpillar), pupa, and adult. Larvae newly emerged from eggs <br />immediately search out suitable hiding places such as under a rock where they enter a <br />physiological resting stage, referred to as diapause, to survive the dry season and await the next <br />rainy season when the larval food plant, Viola, sprouts new foliage and becomes edible, typically <br />in late January to early February. Many of the young die during diapause. Surviving larvae will <br />continue to periodically feed during the next four months, after which they will pupate and <br />transform into adult butterflies. <br />The adult flight season typically begins in mid-May and ends in mid-July, although actual <br />starting and ending times can vary by a few weeks from year-to-year and in different locations <br />depending upon seasonal and microclimate weather variations. The average adult life span has <br />been shown through a capture/recapture study to be about 5-7 days, but individuals have lived in <br />a lab environment for as long as two weeks. <br />Because of the length of the flight season, adults may forage on nectar from the flowers of <br />several different plant species as these plants flower at different times during the flight season. <br />Preferred nectar species include native species such as bee balm (Monardella spp.) and <br />California buckeye (Aesculus californica), but also include non-native (and often invasive) <br />species such as Silybum marianum, Carduus pycnocephalus, and Cirsium vulgare. Because <br />Silybum blooms earlier than the other species, it is utilized earliest in the flight season, while <br />Aesculus is used during the middle, and Monardella is used towards the end of the <br />season. While these latter species are the preferred nectar plants for the silverspot, the butterfly <br />will utilize nectar from other plant species depending upon their availability at a particular <br />location. Varied topography within the butterfly’s habitat tends to extend the blooming season <br />of individual nectar plant species and therefore increase the value of such habitat for the <br />butterfly.