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Scolia dubia

By Bryan Barzaga and Chelsea Gittle

Geographic Range

This species ranges throughout most of the southern United States from New England to Florida to beyond the Rocky Mountains. ("The North Carolina Agricultural Extension Service", 1998; Grissell, 2007)

Habitat

This wasp is found in temperate habitats across the southern half of the United States. A basic requirement is soil with grubs. Large populations of this species are associated with large populations of Cotinus nitida, the green June beetle, for example. They are often found in fields, meadows, or lawns where grubs are abundant and easily found. ("The North Carolina Agricultural Extension Service", 1998)

Physical Description

The adults have black antennae (longer on males) with a shiny bluish-black head, thorax, and fore-abdomen. On each side of the abdomen is a yellow spot (absent sometimes). Their black wings look blue in some light, hence the common name blue-winged wasps. Their bodies are fairly hairy and beyond the spots their abdomen appears more brownish with red hairs. The antennae, maxillary and labial palps are one-segmented. There is a slit-like silk gland on the labium. Adults measure 20 to 25 mm in length. Larva is a white, legless grub with a brown head. (Grissell, 2007; Malinoski, 1990)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    20 to 25 mm
    0.79 to 0.98 in
  • Average length
    23 mm
    0.91 in

Development

Eggs hatch on grubs paralyzed by their mother. The larva feeds on the grub for about a week and then spins a cocoon. The wasp likely overwinters in this pupal state and emerges as an adult after approximately 3 weeks. (Brandenberg and Basker, 2000; Grissell, 2007; Robinson, 1943)

Reproduction

Both sexes of Scolia dubia are reported to perform mating dances. These dances consist of flying inches above the ground in figure eight patterns. Little additional information is known regarding mating systems for this species. (Grissell, 2007)

Scolia dubia breeds once yearly between April and November, depending on geographic location. Once fertilized, the female begins searching for a host to lay her egg upon. She locates a grub by burrowing through the soil using her mandibles and spiny legs. When she finds a host she will sting it in the neck, paralyzing it. She will then implant her egg on the third segment of the grub. When the larva hatches about a week later it will use the grub as a fresh food supply. A larva completes metamorphosis and emerges above ground as an adult after approximately 3 weeks. (Barratt, 2003; Robinson, 1943)

  • Breeding interval
    Scolia dubia breeds once yearly.
  • Breeding season
    Depending on the region it can be anywhere from April to November.
  • Average eggs per season
    1-2 egg(s) per day for 2 months
  • Average gestation period
    1 weeks

Females provide a food source and a nest to nourish and protect their young during development. The female lays the fertilized egg in or on a grub shortly after mating. Females will dig underground tunnels to reach suitable grub hosts. Females will construct a cell surrounding the grub to serve as a space for her larvae to grow and develop after hatching. Sometimes before laying her egg, the female drags the grub deeper in the soil. After initial fertilization, males provide no parental care. ("The North Carolina Agricultural Extension Service", 1998; Barratt, 2003; Brandenberg and Basker, 2000; Flanders and Cobb, 2000; Grissell, 2007)

  • Parental Investment
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

Once the larvae hatch from cocoons, the wasps only live for one season. Blue-winged wasps are in their adult phase for just 4 to 5 months. (Barratt, 2003)

  • Typical lifespan
    Status: wild
    4 to 5 months

Behavior

These wasps often aggregate in groups. Male wasps can be found flying low to the ground in groups of about a dozen. This species is diurnal and is only active above ground during the summer months, with peak activity occurring in mid- to late summer. Blue-winged wasps only live and breed for one season. They are a parasitic species that lays eggs on a paralyzed, grub host that is later consumed by the developing larvae. (Grissell, 2007)

Home Range

Information on the home range of this wasp was unavailable. ("The North Carolina Agricultural Extension Service", 1998)

Communication and Perception

Scolia dubia has compound eyes and antennae which are used to perceive the environment. They recognize opposite sex because of slight sexual dimorphism in antennae length, and possibly through the use of pheromones. This species uses a courtship dance consisting of flying in a figure eight pattern to communicate with and attract mates. (Barratt, 2003; Gordh and Headrick, 2001)

Food Habits

Scolia dubia larvae are born on green June beetle (Cotinis nitida) and Japanese beetle grubs (Popillia japonica). Females paralyze a grub which serves as the primary food source for developing larvae. Adults feed on flower nectar. ("The North Carolina Agricultural Extension Service", 1998; Borror and White, 1970)

  • Animal Foods
  • insects
  • Plant Foods
  • nectar

Predation

Scolia dubia is prey to birds and predatory insects. Its means of defense as an adult is its sting, which can be handled by experienced predators. Coloration, specifically the yellow abdomen spots, may serve as a warning of the wasps' ability to sting. (Borror and White, 1970)

Ecosystem Roles

Scolia dubia is parasitic upon larvae of beetle grubs including those of green June beetles and Japanese beetles. These two beetle species can cause considerable damage to plants in their ecosystems, and thus Scolia dubia help to keep populations under control and ecosystems healthy. These wasps have been introduced as biological control against Japanese beetles in areas where beetle populations were too abundant. Scolia dubia also consume nectar as adults, and thus may serve as a pollinator for flower species it feeds upon. (Grissell, 2007)

Species Used as Host

Economic Importance for Humans: Positive

This species can be an indication of grub infestation and can also be used as a control method of a beetle grub infestation. Scolia dubia populations have been introduced as biological control for some species of white grubs. They also may aid slightly in the pollination of wild flowers. ("The North Carolina Agricultural Extension Service", 1998; Borror and White, 1970; Grissell, 2007)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

Scolia dubia rarely stings people and is not aggressive unless provoked. (Brandenberg and Basker, 2000)

Conservation Status

Scolia dubia is common and abundant in its wide geographical range. This abundance likely makes this species of least concern to many conservation initiatives. ("The North Carolina Agricultural Extension Service", 1998; Malinoski, 1990)

Contributors

Bryan Barzaga (author), Rutgers University, Chelsea Gittle (author), Rutgers University, David V. Howe (editor), Rutgers University, Rachelle Sterling (editor), Special Projects.

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.

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

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

diapause

a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

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

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

herbivore

An animal that eats mainly plants or parts of plants.

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.

native range

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

nectarivore

an animal that mainly eats nectar from flowers

oviparous

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

parasite

an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

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.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

suburban

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

tactile

uses touch to communicate

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

1998. "The North Carolina Agricultural Extension Service" (On-line). Scoliid Wasps. Accessed November 11, 2007 at http://ipm.ncsu.edu/AG268/html/scoliid_wasps.htm.

Barratt, B. 2003. Aspects of Reprodutive Biology and Behavior of Scoliid Wasps. Doc Science Internal Series, 147: 1-11. Accessed November 11, 2007 at http://www.doc.govt.nz/upload/documents/science-and-technical/dsis147.pdf.

Borror, D., R. White. 1970. Insects. Boston: Houghton Mifflin Company.

Brandenberg, R., J. Basker. 2000. "North Carolina State University" (On-line). Ornamentals and Turf. Accessed November 11, 2007 at http://www.ces.ncsu.edu/depts/ent/notes/O&T/lawn/note12/note12.html.

Flanders, K., P. Cobb. 2000. "Alabama Cooperative Extension Program" (On-line). Biology and Control of the Green June Beetle. Accessed November 11, 2007 at http://www.aces.edu/pubs/docs/A/ANR-0991/.

Gordh, G., D. Headrick. 2001. A Dictionary of Entomology. United Kingdom: Biddles Ltd, Guildford and King's Lynn.

Grissell, E. 2007. "University of Florida IFAS Extension" (On-line). Scoliid Wasps. Accessed November 11, 2007 at http://entnemdept.ifas.ufl.edu/creatures/misc/wasps/scoliid_wasps.htm.

Malinoski, M. 1990. "Maryland Cooperative Extension" (On-line pdf). Accessed November 11, 2007 at http://www.hgic.umd.edu/_media/documents/hg104_000.pdf.

Robinson, W. 1943. Urban Insects and Arachnids. Cambridge, UK: Cambridge University Press.

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