Endangered Insects and Spiders - Butterflies

Like amphibians, many butterflies and moths are considered by scientists to be "indicator species" because they are particularly sensitive to environmental degradation. The decline of these species serves as a warning to human beings about the condition of the environment. Part of the reason butterflies are sensitive to many aspects of the environment is that these species undergo a drastic metamorphosis, or change, from larva to adult as a natural part of their life cycles. Butterfly larvae are generally crawling, herbivorous caterpillars, whereas butterfly adults fly and are nectar-eating. Butterflies can thrive only when intact habitats are available for both caterpillars and adults. Consequently, healthy butterfly populations tend to occur in areas with healthy ecosystems. Because many species are extremely sensitive to changing environmental conditions, the 20,000 known species of moths and butterflies are carefully monitored by scientists and conservationists around the world.

Butterflies and moths have alerted scientists to numerous habitat changes. In southern Florida, for example, the sharp decline of swallowtail butterflies alerted biologists to the harm caused by mosquito sprays, as well as to the fact that pesticides had contaminated the water. In 1996 scientists in Michigan and England reported in the Journal of Heredity (September/October 1996), that during the 1960s, darker-colored moths began to predominate over light, white-and-black-flecked moths in polluted areas. This was seen in both England and the United States and was probably due to the fact that darker moths were better able to "blend in" to the dingy environment and hide from predators. In both countries, clean air laws were passed and decreases in pollution resulted. Now, in both countries, lighter-colored moths are again predominant. Dr. Douglas Futuyma, a biologist at the State University of New York at Stony Brook, reported that other insect species have shown increases in the proportion of darker-colored individuals in industrialized areas, a phenomenon called "industrial melanism." In those species, as well, the proportion of dark specimens drops as air quality improves.

In many cases, butterflies also help conservationists decide where to locate parks and nature refuges. Generally, the more varieties of butterflies that exist in an area, the more species of other animals and plants will live there too. Unfortunately, many butterfly species are disappearing around the world.

Monarch Butterfly

Historically, monarch butterflies migrated by the millions on a 3,000-mile journey up and down the North American continent. Over time, monarch butterfly populations have also become established in Australia and on the Pacific islands of Samoa and Tahiti. Other monarch populations have appeared in Hawaii and New Zealand.

TABLE 9.1
Endangered or threatened insects and spiders, February 2004

Status	Species name	Status	Species name
Insects
E	Beetle, American burying (Nicrophorus americanus)	E	Butterfly, Uncompahgre fritillary (Boloria acrocnema)
E	Beetle, Coffin cave mold (Batrisodes texanus)	E	Dragonfly, Hine's emerald (Somatochlora hineana)
E	Beetle, Comal Springs dryopid (Stygoparnus comalensis)	E	Fly, Delhi Sands flower-loving (Rhaphiomidas terminatus abdominalis)
E	Beetle, Comal Springs riffle (Heterelmis comalensis)	E	Grasshopper, Zayante band-winged (Trimerotropis infantilis)
T	Beetle, delta green ground (Elaphrus viridis)	E	Ground beetle, [unnamed] (Rhadine exilis)
E	Beetle, Helotes mold (Batrisodes venyivi)	E	Ground beetle, [unnamed] (Rhadine infernalis)
E	Beetle, Hungerford's crawling water (Brychius hungerfordi)	E	Moth, Blackburn's sphinx (Manduca blackburni)
E	Beetle, Kretschmarr cave mold (Texamaurops reddelli)	T	Moth, Kern primrose sphinx (Euproserpinus euterpe)
E	Beetle, Mount Hermon June (Polyphylla barbata)	T	Naucorid, Ash Meadows (Ambrysus amargosus)
E	Beetle, Tooth cave ground (Rhadine persephone)	E	Skipper, Carson wandering (Pseudocopaeodes eunus obscurus)
T	Beetle, valley elderberry longhorn (Desmocerus californicus dimorphus)	E	Skipper, Laguna Mountains (Pyrgus ruralis lagunae)
T	Butterfly, bay checkerspot (Euphydryas editha bayensis)	T	Skipper, Pawnee montane (Hesperia leonardus montana)
E	Butterfly, Behren's silverspot (Speyeria zerene behrensii)	T	Tiger beetle, northeastern beach (Cicindela dorsalis dorsalis)
E	Butterfly, callippe silverspot (Speyeria callippe callippe)	E	Tiger beetle, Ohlone (Cicindela ohlone)
E	Butterfly, El Segundo blue (Euphilotes battoides allyni)	T	Tiger beetle, Puritan (Cicindela puritana)
E	Butterfly, Fender's blue vIcaricia icarioides fenderi)	Arachnids
E	Butterfly, Karner blue (Lycaeides melissa samuelis)
E	Butterfly, Lange's metalmark (Apodemia mormo langei)	E	Harvestman, Bee Creek cave (Texella reddelli)
E	Butterfly, lotis bluev (Lycaeides argyrognomon lotis)	E	Harvestman, Bone cave (Texella reyesi)
E	Butterfly, mission blue (Lcaricia icarioides missionensis)	E	Harvestman, Cokendolpher cave (Texella cokendolpheri)
E	Butterfly, Mitchell's satyr (Neonympha mitchellii mitchellii)	E	Meshweaver, Braken bat cave (Cicurina venii)
E	Butterfly, Myrtle's silverspot (Speyeria zerene myrtleae)	E	Meshweaver, Government Canyon bat cave (Cicurina vespera)
T	Butterfly, Oregon silverspot vSpeyeria zerene hippolyta)	E	Meshweaver, Madla's cave (Cicurina madla)
E	Butterfly, Palos Verdes blue (Glaucopsyche lygdamus palosverdesensis)	E	Meshweaver, Robber baron cave (Cicurina baronia)
E	Butterfly, Quino checkerspot (Euphydryas editha quino [=E. e. wrighti])	E	Pseudoscorpion, Tooth cave (Tartarocreagris texana)
E	Butterfly, Saint Francis' satyr (Neonympha mitchellii francisci)	E	Spider, Government Canyon bat cave (Neoleptoneta microps)
E	Butterfly, San Bruno elfin (Callophrys mossii bayensis)	E	Spider, Kauai cave wolf or pe'e pe'e maka 'ole (Adelocosa anops)
E	Butterfly, Schaus swallowtail (Heraclides aristodemus ponceanus)	E	Spider, spruce-fir moss (Microhexura montivaga)
E	Butterfly, Smith's blue (Euphilotes enoptes smithi)	E	Spider, Tooth cave (Neoleptoneta myopica)
E = Endangered
T = Threatened
SOURCE: Adapted from "U.S. Listed Invertebrate Animal Species Report by Taxonomic Group as of 02/17/2004," Threatened and Endangered Species System (TESS), U.S. Fish and Wildlife Service, Washington, DC, 2004 [Online]http://ecos.fws.gov/tess_public/TESSWebpageVipListed?code=I&listings=0#F [accessed February 17, 2004]

For many years, naturalists sought to pinpoint the location where monarchs hibernate in January and February in preparation for their mating season and northward migration in March. In 1975, following an arduous search, a serene monarch hibernation area was located in the high altitude forests of the Michoacán Mountains in Mexico. Mexico declared the impoverished region a protected area. The inhabitants of the area turned the site into an ecotourist attraction in order to generate income for the economy. However, ecotourism not only failed to generate sufficient money to support the people of the area, but also caused severe habitat disruption. The onslaught of tourists affected habitats by introducing excessive noise, tobacco smoke, fire, and pollution. Monarch butterflies are now considered endangered by the IUCN. The U.S. Fish and Wildlife Service and the Mexican government have since attempted to nurture a self-sustaining economy in the monarch hibernation area by introducing fish breeding and horticulture.

In January 2002 a massive die-off of monarch butterflies in their wintering grounds in Mexico became major news worldwide. An estimated 250 million butterflies froze to death following a winter storm. As many as 80 percent of monarch colonies may have succumbed. While the storm may have been directly responsible for the deaths, deforestation and logging near the butterfly habitat are believed to have played a significant role. In particular, a fuller and healthier forest canopy would have better protected individuals from extreme weather. Despite the fact that butterfly hibernation areas are in protected reserves, logging continued there until recently. Although the massive die-off was a huge blow to monarch populations, many individuals did survive and it is hoped that the population will bounce back.

MONARCHS AND THE BIOPESTICIDES DEBATE.

Monarch butterflies have also played an unwitting role in the recent debate regarding genetically modified foods. In an effort to reduce the amount of pesticides in the environment, plant geneticists have developed novel hybrid plants that are genetically altered to produce substances called biopesticides. These plants repel pests without additional application of pesticides. In order to create biopesticide-producing plants, scientists insert DNA for pesticidal proteins directly into plant genomes. The introduction of biopesticides generated continuing controversy in the 2000s. Proponents argued that biopesticides were much less toxic than chemical pesticides, and also claimed that biopesticides affected only targeted plant pests without affecting other consumer organisms. Opponents, however, feared that any genetically altered species posed potential and unknown threats.

These fears were substantiated when researchers discovered that one genetic hybrid of corn, called Bt corn, is poisonous to monarch butterflies. Bt corn is genetically modified to include genes from a known pesticidal bacterium, Bacillus thuringiensis. Pesticidal proteins were genetically spliced into the corn genome to create a hybrid that repelled an important pest, the European corn borer. Bt corn was believed to be safe for the environment because it lacked toxins. Researchers reported, for example, that Bt corn had no effect on honeybees, ladybugs, or other organisms that inhabit cornfields. However, a new study reported in 1999 that in laboratory tests involving monarch caterpillars, as many as 44 percent of the caterpillars died after exposure to Bt corn.

Sacramento Mountains Checkerspot Butterfly

The Sacramento Mountains checkerspot butterfly has a highly specialized habitat—it occurs only in meadows at elevations of between 8,000 and 9,000 feet in southern New Mexico. Furthermore, the species is only found where there are native flowering plants, and is absent from meadows where invasive species have taken over. This is because Sacramento Mountains checkerspot caterpillars feed solely on native plant species such as the New Mexico penstemon. The Sacramento Mountains checkerspot is characterized by brown, red, orange, and white checked wings.

The Sacramento Mountains checkerspot is currently proposed for listing as endangered in its entire range. The species was first petitioned for listing by the Center for Biodiversity in 1999. Surveys of population sizes took place between 1997 and 2000 and revealed that the species occurs only in fragmented populations within a 33-square-mile area in New Mexico. The butterfly was officially proposed for listing in 2001; it remained a proposed species as of 2004. It is threatened primarily by loss of habitat due to urban development and destruction of habitat by off-road vehicles and overgrazing. In addition, several invasive plant species are taking over meadows once occupied by native plant species used by Sacramento Mountains checkerspot caterpillars. Finally, over-collection of specimens has harmed populations. A critical habitat of 5,000 acres is being proposed for the species, half of which is on federal property and half of which lies on private property.

Karner Blue Butterfly

The Karner blue butterfly was listed as endangered in 1992. It once occupied habitats in the eastern United States from Minnesota to Maine as well as Ontario, Canada. At present, the species occurs in portions of Minnesota, Wisconsin, Indiana, Michigan, New York, New Hampshire, and Ohio. Most Karner blue butterfly populations are very small and in danger of extinction.

The caterpillars of the Karner blue butterfly rely for food on a species of lupine that is now found primarily on roadsides, military bases, and some forest areas. (See Figure 9.1 for a description of the Karner blue butterfly life cycle.) The primary reason for endangerment of the Karner blue butterfly is habitat loss due to land development for human use and forest maturation. Table 9.2 shows the recovery objectives, recovery criteria, recovery actions needed, total cost of recovery, and expected date of recovery as set out in the recovery plan for the species completed in September 2003. Figure 9.2 shows the recovery units, or populations, of the species, sites for potential recovery units, as well as other sites where the species has historically been found.

As is the case with other endangered species, conservation measures protecting the habitat of the Karner blue butterfly are expected to benefit numerous others rare species as well. Table 9.3 lists other rare species that overlap with the Karner blue butterfly in habitat in the state of Michigan. These include mammals, birds, reptiles, other insects and invertebrates, and a large number of plants. This is one of many examples of how the Endangered Species Act, despite focusing on individual species, contributes to the conservation of many species and to entire ecosystems.

Blackburn's Sphinx Moth

Blackburn's sphinx moth was first listed as an endangered species in February 2000 and is found exclusively in Hawaii. This moth species is threatened by factors such as urban development, conversion of land for agricultural use, invasive plant species, non-native ungulates (hoofed animals), and invasive predators and parasites. Figure 9.3 shows the estimated pre-human contact range of the species in Hawaii, current points of Blackburn sphinx moth occurrence, and current points of occurrence of the native host plant on which the moth depends. Some of the invasive predators and parasites that impact the species, and the islands on which they are found, are listed in Table 9.4. Conservation recommendations in the species recovery plan, which was drawn up by the Fish and Wildlife Service in October 2003, include habitat conservation and restoration, planting of the moth's host plant in new habitats, and a captive breeding and reintroduction program. The total cost for recovery of the species is estimated at $5.5 million.