Why Have the Butterflies Gone?

Why Have the Butterflies Gone?

Insect pollinators such as butterflies, bees, beetles and moths are in crisis worldwide, suffering from the effects of climate change, pesticide exposure, and habitat loss, fragmentation and degradation. Pollinators make fertilization possible for many plants; without them, some foods would not exist.  To produce fruits, vegetables, nuts, peanuts and chocolate, plants depend on pollinators.
image001Delicate butterflies are important pollinators in Crest’s native chaparral and sage scrub plant communities. Monarches have been in the spotlight lately due to a drastic decline in their numbers, they are down 90 percent from the 20-year average–an historical low since their migration was discovered in the 1970s.
Lack of available host plants has been identified as a key factor in this decline. Local monarch’s plant of choice is narrowleaf milkweed, a plant that once grew prolifically in dry, rolling hills that were also perfect for human development.The Quino checkerspot was once one of the most common butterflies in Southern California. At the beginning of the 20th century, millions of the orange-and-black butterflies could be seen each year from the Santa Monica Mountains to Baja California.image002Rapid development quickly eliminated much of the butterflies’ native habitat and the Quino checkerspot butterfly was federally listed as an endangered species in 1997. The 2003 and 2007 wildfires destroyed what was left of their critical habitat and the butterflies have yet to recover.Fortunately, the Quino checkerspot’s host plants are making a comeback on protected lands such as Crestridge Ecological Reserve. Quino prefer to lay their eggs on dwarf plantain, a tiny, inconspicuous annual that grows in dry, open areas and is easily trampled by off trail users.image003By staying on trails and protecting habitat, we also improve habitat for Hermes copper, a butterfly found only in San Diego County and northern Baja. It is also on the brink of extinction.The species inhabits sage scrub and chaparral and is dependent on its larval host plant, spiny redberry, to complete its lifecycle. Crestridge Ecological Reserve’s redberry population has made a healthy comeback since the Cedar Fire, providing habitat for adult necturing and egg-laying.Harbison’s dun skipper—a butterfly that sits with its wings folded over its back—is another Crest native that’s numbers have greatly declined. They are found in chaparral or oak riparian areas with drainages that support their host plant, San Diego sedge.

Dun skipper larvae bend and “sew” the long sedge leaves together to create a hibernaculum, a place to shelter while over wintering or feeding.

image004EDI volunteers and students have been supplementing the sedge population in the creek bed that runs through the riparian oak woodland at CER.  But continued drought is causing the loss of habitat for the dun skipper, as creeks, wetlands and springs dry up.

Urban sprawl, wildfires and climate change are a triple threat to butterflies and other pollinators, but you can make a difference by protecting habitat, planting natives and limiting the use of pesticides. Join EDI on the Crestridge Ecological Reserve and help protect habitat for all pollinators and their host plants.


San Diego Sensitive Butterflies

Butterflies of SD County known food plants

Quino checkerspot

Hermes copper butterfly

Harbinson’s dun skipper

Monarch butterflies:
Answers From the Monarch Butterfly Expert

The Monarch Butterfly Story…

Xerces Monarch Webpage

Conservation Status and Ecology of Monarchs in the Western US

Western monarch conservation

Guide to Milkweeds and Monarchs in the Western US

Project Milkweed

Milkweed Seed Finder

Milkweed Conservation Practitioners Guide

Guide to California Native Milkweeds

Western Monarch Thanksgiving Count

Review of Laws & Regulations Affecting California Monarch Habitat

Potential risks of growing exotic (non-native) milkweeds for monarchs

Plant Milkweed for Monarchs (guide to regionally native milkweed plants)

All Monarch Joint Venture resources