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Eurosta solidaginis

By Sara Diamond and Elisabeth Reyna

Geographic Range

The goldenrod gall fly is found in eastern and midwestern North America. (Weis and Abrahamson, 1998; Williams, 2001)

Habitat

The entire life cycle of Eurosta solidaginis is closely connected to the goldenrod plant. Goldenrod gall flies can be found where there is goldenrod in the northeastern and midwestern portions of North America. (; Weis and Abrahamson, 1998)

Physical Description

The adult goldenrod gall fly is tawny in color with speckled wings and is about five mm long. Females are slightly larger than males. Eurosta solidaginis shares many characteristics with its close relatives, the fruit flies (Melanogaster), such as a wide head and large, compound iridescent eyes. (; Moran, 2005; Weis and Abrahamson, 1998)

  • Sexual Dimorphism
  • female larger
  • Average length
    5 mm
    0.20 in

Development

The eggs hatch between seven and ten days after being oviposited in the terminal bud of a goldenrod plant. The larva then chews through the bud and down into the stem. There the saliva of the larva stimulates the plant to form a gall. The inside of the gall is rich in protein and starch, and the larva feeds off this as it matures. As the larva grazes on this inner layer, the plant compensates for the nuitrient loss by sending more nutrients to the inner wall lining of the stem, maintaining the larval food source. In the fall, the outside of the gall becomes dry and corky, forming a protective layer. The maggot will chew an a hole to the outside, although it wont actually emerge untill the following spring. After overwintering inside of the gall, the maggot pupates in spring, emerging from the gall as an adult. (; Moran, 2005; Weis and Abrahamson, 1998)

Reproduction

Males sit waiting for females on the tip of goldenrod plants. When a female is attracted to a particular male, she will fly over to him, they will copulate, and then she flies away again to lay her eggs. He attracts the female by dancing, or making a special display that consists of flicking his wings. (Weis and Abrahamson, 1998)

After mating, the female inserts her fertilized eggs using a tube-like structure called the ovipositor into the terminal bud of a goldenrod plant. A female goldenrod gall fly can lay up to one hundred eggs. (Moran, 2005; Weis and Abrahamson, 1998)

  • Range eggs per season
    100 (high)

After eggs are layed in suitable locations for larval success, there is no further parental investment.

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female

Lifespan/Longevity

The life of a Goldenrod Gall Fly consists of fifty weeks as a larva living inside of the gall, and two weeks as an adult. (Weis and Abrahamson, 1998)

  • Average lifespan
    Status: wild
    1 years

Behavior

The female gall fly will fly from plant to plant searching for the perfect host for her offspring. When she lands, she inserts her ovipositor into the plant and "tastes" the host with her reproductive organs and her feet. If the host plant is not suitable, she flies on and tries another plant. (Weis and Abrahamson, 1998)

Communication and Perception

The main communication between gall flies occurs while the female is searching for a mate. The male sits on the tip of a goldenrod plant and flicks his wings in a way that attracts the female and entices her to fly over and mate with him. (Weis and Abrahamson, 1998)

  • Communication Channels
  • visual

Food Habits

Larvae feed off of the protein-and-starch rich inner layer of the gall. The gall provides all of the food necessary for the growth and development of the maggot. Adults do not eat at all. (Moran, 2005; Weis and Abrahamson, 1998)

  • Plant Foods
  • wood, bark, or stems

Predation

While the adult gall fly has few predators, the maggot is consumed by a great variety of animals. Some birds, such as the downy woodpecker (Picoides pubescens), and carolina chickadee (Parus carolinensis) will break open galls to eat the larva during winter months when food is more difficult to find. Other insects will also attack the larvae. The larvae of Mordellistena unicolor, a type of beetle, also prey upon gall fly larvae. Eurytoma gigantea and Eurystoma obtusiventris are two wasp species who lay their eggs inside goldenrod galls. When the eggs hatch, the wasp larvae feed upon the developing Eurosta solidaginis. (Moran, 2005; Shealer, et al., 1999)

Ecosystem Roles

The goldenrod gall fly reduces seed yield in affected plants. The larvae of the insect provide food for birds and squirrels during the winter months. Galls formed by Eurosta solidaginis provide a home for certain species of parasitic wasps and beetles. (Cappuccino, 1992; Shealer, et al., 1999; Weis and Abrahamson, 1998)

  • Ecosystem Impact
  • creates habitat

Economic Importance for Humans: Positive

Scientists are currently studying the goldenrod gall fly to see if it will provide ways to preserve organs used for transplants. The gall fly larva survives long periods of time in extremely cold climates. The larva produces the cryoprotective compounds glycerol and sorbitol, which prevents the larvae from freezing to death during the winter months by preventing ice formation within cells. Scientists have been able to use these compounds to freeze collections of like cells and preserve cells in sperm and blood banks, sometimes for several years. (Barnes-Svarney, 1992)

Economic Importance for Humans: Negative

There is no known negative economic impact caused by the goldenrod gall fly.

Conservation Status

This particular species is in no real danger of becoming endangered or extinct. (Cappuccino, 1992)

Contributors

Sara Diamond (author, editor), Animal Diversity Web.

Elisabeth Reyna (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

semelparous

offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

1993. Fruit Fly. Columbia Encyclopedia, 5th Edition.

Barnes-Svarney, P. 1992. Insects in Deep Freeze. Technology Review, v. 95 no 3: 20.

Cappuccino, N. 1992. The Nature of Population Stability in Eurosta solidaginis, a Nonoutbreaking Herbivore of Goldenrod. Ecology, v. 73 no. 5: 1792-1801.

Moran, M. 2005. "Goldenrod Gall Fly" (On-line). Study of Northen Virginia Ecology. Accessed October 07, 2008 at http://www.fcps.edu/islandcreekes/ecology/goldenrod_gall_fly.htm.

Shealer, D., J. Snyder, V. Dreisbach. 1999. Foraging Patterns of Eastern Grey Squirrels (Sciurus carolinenis) on Goldenrod Gall Insects, a Potentially Important Winter Food Source.. The American Midland Naturalist, v.142 no 1: 102-109.

Weis, A., W. Abrahamson. 1998. Just Lookin' for a Home. Natural History, v. 107 no7: 60-63.

Williams, T. 2001. Earth Almanac: The Gall of Goldenrod. Audubon, January-February. Accessed October 07, 2008 at http://www.audubonmagazine.org/earthalmanac/almanac0101.html.

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