California’s Butterflies

Lange’s Metalmark

At Right: An adult Mormon Metalmark butterfly (Apodemia mormo mormo). The Mormon Metalmark is a close relative of the Lange’s Metalmark.

The Lange’s Metalmark butterfly (Apodemia mormo langei) is restricted to the Antioch Dunes of Contra Costa County, California.  This metalmark belongs to a complicated group of butterflies that are still poorly understood.  The habitat has been greatly reduced by the mining of its sands since the San Francisco Earthquake of 1906.  Now most of the sands, which many of the endemic plants are adapted to, are largely gone and only a thin grey layer of sand still exists.  The food plant for the metalmark is called naked buckwheat (Eriogonum nudum auriculatum).  This butterfly has only a single flight from mid August to early October.

Life History

The Lange’s Metalmark Butterfly belongs to a group within the mormo complex that diapause as a young larva inside an egg.  These eggs are 50% larger than eggs from other taxa.  The diapausing young larva remains in the egg for several months.  Due to some environmental stimuli, such as accumulated temperature in the form of degree days, the young larvae break diapause and start feeding.  The time at which larvae break diapause is believed to be sometime between January and March.  The larvae feed and grow until at least June.  In July and August the larvae pupate and the adults emerge from mid August to mid September.  During that time these butterflies mate and the females oviposit.  The eggs are placed in a number of sites on and around food plants.

Diapause

This species is known to diapause as a young larva inside an egg.  The eggs hatch sometime in early to late winter.  It is not clear whether there is a second diapause as a fourth instar and perhaps a sixth instar larva.  Larvae have been observed in the field to be delayed in development and possibly enter a second year diapause.  Presumably these larvae enter diapause and do not eclose the first year; they wait until the second year.  If this does happen, it is not clear how the larvae resynchronize themselves to the normal population.  This resynchronization could happen by a last instar summer diapause.  This late instar diapause could be under photoperiod regulation and respond to long days becoming short days, which occurs in late June and extends into July.  After this period diapause could finish and initiate the pupation period.  This aspect of Lange’s Metalmark development needs to be investigated further.

Mating

Behr’s Metalmark butterflies (a close relative of the Lange’s Metalmark) are being used as a surrogate species to identify the conditions needed to stimulate mating in the lab.  In the summer of 2007, over one hundred larvae were reared in captivity.  Most of those larvae pupated and formed adults.  From them only one captive breeding pair was obtained.  More larvae are being reared at this time to repeat this study.  The single fertilized female Behr’s Metalmark produced 157 eggs.  Most of the larvae from this mating are presently in diapause.  Many larvae went into a fourth instar diapause.

 

These larvae are also being used for experiments.  Dr. Pratt has observed that larvae of the mormo complex often grow faster in the lab than they do in the field.  Currently, Behr’s Metalmark larvae are being placed in the refrigerator for a variety of periods: one week, two weeks, three weeks, or four weeks.  These groups will be compared to control larvae reared at room temperature to determine the degree that larval development can be slowed in the lab by periods of chilling.  Care must be taken, since long term chilling could also cause mortality.

Feeding

In nature this species largely nectars or feeds upon the flowers of the buckwheat food plant, the naked buckwheat (Eriogonum nudum auriculatum).  Various members of the Asteraceae, particularly species with yellow flowers, are also used to some extent.  Nectar probably plays a big role in the quantity of eggs produced by the female Lange’s Metalmark butterflies.  Captive adult female Lange’s Metalmark butterflies are fed a 1:3 buckwheat honey to water mixture.

 

The larvae feed specifically on the naked buckwheat (Eriogonum nudum auriculatum).  In the first couple of instars the larvae often feed on the younger leaves.   During the following four instars the larvae scrape the dorsal surface of the large leaves of the buckwheat.  This feeding behavior is rather distinct.

Lab Colonies

There are lab colonies of this butterfly in Moorpark, CA and Murrieta, CA.

 

 

 

 

Above, At Left: A fourth instar Lange’s Metalmark larva.

Above, At Right: A Behr’s Metalmark pupa.