Sacramento Mountains Checkerspot Butterfly

The Sacramento Mountains checkerspot butterfly inhabits high-altitude meadows in the upper-montane and subalpine zone at elevations between 2,380 and 2,750 m (7,800 and 9,000 ft) (Service et al. 2005, p. 9). The ecosystem at this elevation usually is cool and wet, supporting diverse and robust plant life, including the butterfly’s preferred host plant: New Mexico beardtongue (Penstemon neomexicanus). It is likely that the meadow habitat upon which the Sacramento Mountains checkerspot butterfly relies were spatially dynamic, driven by a historical fire regime (Brown et al. 2001, pp. 116–117).

The larval host plant for the Sacramento Mountains checkerspot butterfly is the New Mexico beardtongue (Ferris and Holland 1980, p. 7). This plant is a member of the Plantaginaceae, or figwort family (Oxelman et al. 2005, p. 425). These perennial plants prefer wooded slopes or open glades in ponderosa pine and spruce/fir forests at elevations between 1,830 and 2,750 m (6,000 and 9,000 ft) (New Mexico Rare Plant Technical Council 1999, entire). New Mexico beardtongue is native to the Sacramento Mountains within Lincoln and Otero Counties (Sivinski and Knight 1996, p. 289). The plant is perennial, has purple or violet-blue flowers, and grows to be 0.5 m (1.9 ft) tall. New Mexico beardtongue prefers areas with loose soils or where there has been recent soil disturbance, such as eroded banks and pocket gopher burrows (Pettinger and Yori 2003, p. ii).

Some plant species within the figwort family, including the New Mexico beardtongue, contain iridoid glycosides, a family of organic compounds that are bitter and emetic (vomit-inducing) for most birds and mammal species. The Sacramento Mountains checkerspot and other subspecies of E. anicia sequester the iridoid glycosides as caterpillars. It is believed that these compounds make the larvae and adult butterflies unpalatable to predators (Gardner and Stermitz 1987, pp. 2152–2167). 

Females deposit a cluster of eggs on the underside of New Mexico beardtongue leaves.  A female can lay two to three sets of eggs during her short lifetime (Ryan 2021a, pers. comm.).  The eggs hatch within two weeks, and larvae collectively create a protective silken shelter, known as a tent, over the host plant feeding upon it until winter or the plant is defoliated (Pratt and Emmel 2010, p. 108).  Pre-diapause caterpillars are relatively immobile and rely on host plant health and abundance to complete the first stages of their life cycle (Arriens et al. 2020, p. 2).  Caterpillars can leave the plant and search for additional resources, but it is unknown how far they can travel in search of food (Pratt and Emmel 2010, p. 108; Service et al. 2005, p. 11).

After the third or fourth instar, the larvae enter a period of arrested metabolism known as diapause.  Diapause occurs between late September and early October, depending on environmental conditions.  The larvae remain in diapause until warm spring temperatures, moisture events, host plant growth, or some combination of these events prompts individuals to come out of their suspended state (Service et al. 2005, p. 11).  There are aspects of diapause that are not well understood as Sacramento Mountains checkerspot butterfly diapause has never been studied.  For instance, it might be possible for caterpillars of the Sacramento Mountain checkerspot butterfly to re-enter or remain in diapause for more than one year if environmental conditions are not conducive for growth (Service et al. 2005, p. 11).  Other species of checkerspot can re-enter or remain in diapause when environmental conditions are not conducive to completing a full life cycle, such as dry years when vegetation is limiting.  These individuals can then come out of diapause the following year when conditions are suitable for growth (Pratt and Emmel 2010 p. 108).

In early spring (March–April), post-diapause larvae emerge and begin to feed again.  In the spring, larvae are more mobile than they were in the fall, moving on average 2.6 meters (8.5 ft) from their natal tents.  They grow through three or four more instars before pupating (form a chrysalis).  Precisely what triggers caterpillars to initiate pupation is not well understood, but likely relies on various environmental cues (Ryan 2021a, pers. comm.).  As many as 98 percent of individuals do not survive to the adult stage (Ryan 2021b, pers. comm.).  Similar mortality rates are typical in other butterflies, as the caterpillars are vulnerable to predation (Swengel 1997, p. 5). 

Changes to the timing of precipitation, such as those caused by climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Learn more about climate change , can result in a phenological mismatch, and can disrupt the butterfly’s lifecycle.  We discuss this more in section 3.2.2.3 Climate Change.