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Stiretrus anchorago

What do they look like?

Anchor stink bugs can be many different colors, from all steel blue to blue-black with red, orange and cream markings, to reddish brown with yellow markings. Others are red behind their head with a blue-black stripe down the middle. They also go through 5 stages of development before they become adults, and their colors change as they develop. Different parts of their bodies change between black, red, and yellow. Anchor stink bugs are easy to tell apart because part of their body called a scutellum is large and shaped like the letter "U", just like in a shield bug. (Blatchley, 1926; McPherson, 1982; Oetting and Yonke, 1971; Richman and Mead, 2008)

  • Sexual Dimorphism
  • female larger
  • Range length
    7 to 11.5 mm
    0.28 to 0.45 in

Where do they live?

Anchor stink bugs live in North America from the north in Ontario, Canada and New England, south to Florida and Mexico. They are found as far west as Iowa, Kansas, and Texas. They have also been found in California. (Blatchley, 1926; McPherson, 1982)

What kind of habitat do they need?

Anchor stink bugs live mostly in open areas like waste areas, old fields, and farm fields. They live on plants where they find insects to eat. They are also found along the edges of groups of trees and wet marsh areas in Florida. (Blatchley, 1926; Howard and Landis, 1936; McPherson and Mohlenbrock, 1976; McPherson, 1982; Oetting and Yonke, 1971; Richman and Mead, 2008; Richman and Whitcomb, 1978; Waddill and Shepard, 1975)

How do they grow?

Like most true bugs, anchor stink bugs start life as eggs, grow and develop as juveniles, and later become adults. The eggs take 8 to 11 days to hatch. They go through 5 stages of development before they become adults, which are called instars. Each of these lasts 3 to 15 days. There are two generations of anchor stink bugs per year. Adults of one generation lay eggs in early spring. The second generation starts laying eggs in late May or early June. Females lay several groups of eggs about 4 days apart. Females lay eggs in a double row, and there are 11.4 eggs in a group on average. The eggs are oval-shaped with ridges, and are almost black. They are 1.30 mm long and 1.03 mm around on average. In the second stage of development they start to eat smaller insects. They stop eating about 2 days before each time they go through another stage of development. (Blatchley, 1926; McPherson, 1982; Oetting and Yonke, 1971; Rebagliati, et al., 2005; Richman and Mead, 2008; Richman and Whitcomb, 1978; Waddill and Shepard, 1974)

How do they reproduce?

Anchor stink bugs have 2 generations each year in most places where they live. They live by themselves except during mating. Males and females mate have more than one mate. They attract mates by releasing chemicals from underneath their abdomen. (Aldrich, et al., 1986; Kochansky, et al., 1989; Oetting and Yonke, 1971; Richman and Whitcomb, 1978; Waddill and Shepard, 1974)

Anchor stink bugs mate and lay eggs the whole time they are alive. Females lay groups of about 11.4 eggs. The lay a total of about 68 to 70 eggs while they are alive. There are two generations of anchor stink bugs each year. The first generation mates from early spring to May and the second generation mates from late May or early June through fall. They are independent from their parents right after they hatch. (Oetting and Yonke, 1971; Richman and Mead, 2008; Richman and Whitcomb, 1978; Waddill and Shepard, 1974)

  • How often does reproduction occur?
    Individuals breed continuously as adults, with adults occurring early in the season through about June and starting again in early August. Females lay eggs about every 4 days during the mating season.
  • Breeding season
    Adults mate continuously while alive, from early in season to about June, and then from early August into the fall.
  • Average eggs per season
    about 68-70
  • Range gestation period
    8 to 11 days

Anchor stink bugs don't invest time or energy into their young after they lay eggs. (Oetting and Yonke, 1971; Richman and Whitcomb, 1978; Waddill and Shepard, 1974)

  • Parental Investment
  • pre-hatching/birth
    • provisioning
      • female

How long do they live?

Anchor stink bugs only live a few weeks or months. When they are raised in captivity, the eggs take 8 to 11 days to hatch. Their first stage of development is 4 to 8 days, the second 3 to 8 days, the third 3 to 7 days, the fourth 4 to 6 days, and the fifth 7 to 15 days. The adults often live through the summer, so they live about a few weeks as adults. The second generation lives through the winter, but is inactive most of the time they're alive. (McPherson, 1982; Oetting and Yonke, 1971)

How do they behave?

Anchor stink bugs live by themselves. They move around hunting for prey. Like most stink bugs, they have wings when they are adults but don't usually fly. (Blatchley, 1926; McPherson, 1982)

Home Range

Anchor stink bugs don't have territories or particular home ranges. (Blatchley, 1926; McPherson, 1982; Richman and Mead, 2008)

How do they communicate with each other?

Like many insects, anchor stink bugs communicate using their senses of sight and smell. Males release a chemical that attracts both females and other males from farther away. They probably use their sense of sight to find each other when they are closer together. They probably smell using their antennae. Like all stink bugs, they give off a musty smell when humans touch them. This is probably used to fend off predators. (Aldrich, et al., 1986; Blatchley, 1926; Kochansky, et al., 1989; McPherson, 1982; Rebagliati, et al., 2005; Staddon, 1979)

What do they eat?

Anchor stink bugs begin eating insects in their second phase of development. They eat larvae of moths and butterflies and beetles. They stab the larvae with their beak, spit out digestive chemicals, and then suck up the digested larvae. Moths and butterflies they eat are black swallowtails, sleepy orange butterfiles, Baltimore checkerspot butterflies, soybean loopers, cabbage loopers, gypsy moths, and tent caterpillars. Beetle larvae they eat are alfafa weevils, Mexican bean beetles, squash beetles, Colorado potato beetles, sumac flea beetles, green tortise beetles, ragweed leaf beetles, leaf beetles, spotted asparagus beetles, cottonwood leaf beetles, and elm leaf beetles. (Blatchley, 1926; Dietz, et al., 1976; Eisner and Eisner, 2000; Hayslip, et al., 1953; Howard and Landis, 1936; McPherson and Mohlenbrock, 1976; McPherson, 1982; Oetting and Yonke, 1971; Richman and Mead, 2008; Richman and Whitcomb, 1978; Richman, 1977; Scholtens, 1990; Waddill and Shepard, 1974; Waddill and Shepard, 1975)

  • Animal Foods
  • insects

What eats them and how do they avoid being eaten?

Like all stink bugs, anchor stink bugs give off a musty smell when humans touch them. This is probably used to fend off predators. However, researchers haven't recorded any predators of anchor stinkbugs. (Eger and Ables, 1981; Oetting and Yonke, 1971)

  • These animal colors help protect them
  • aposematic

What roles do they have in the ecosystem?

Anchor stink bugs may impact farms, where they can be pretty common. They also affect the beetles, moths, and butterflies that they eat, and are a significant predator of Baltimore checkerspot butterflies. Their only parasites are tachinid flies. Tachinid fly larvae grows inside adult anchor stink bugs. (Blatchley, 1926; Eger and Ables, 1981; Hayslip, et al., 1953; Howard and Landis, 1936; McPherson, 1982; Oetting and Yonke, 1971; Richman, 1977; Scholtens, 1990; Waddill and Shepard, 1974; Waddill and Shepard, 1975)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

Anchor stink bugs give off a bad smell when humans touch them, but it doesn't have a very serious impact. (Blatchley, 1926; McPherson, 1982; Staddon, 1979)

How do they interact with us?

Anchor stink bugs eat many other bugs that eat soybean and alfalfa crops planted by farmers. This may mean they benefit farming in the southern United States, but researchers haven't been table to show this for sure or not. (DeCoursey and Allen, 1968; Hayslip, et al., 1953; Howard and Landis, 1936; McPherson, 1982; Richman and Mead, 2008; Richman, 1977; Waddill and Shepard, 1974; Waddill and Shepard, 1975)

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

Anchor stink bugs are not endangered or threatened.

Contributors

Brian Scholtens (author), University of Michigan Biological Station, Catherine Kent (editor), Special Projects.

References

Aldrich, J., J. Oliver, W. Lusby, J. Kochansky. 1986. Identification of male-specific exocrine secretions from predatory stink bugs (Hemiptera, Pentatomidae). Archives of Insect Biochemistry and Physiology, 3: 1-12.

Blatchley, W. 1926. Heteroptera or true bugs of eastern North America with especial reference to the faunas of Indiana and Florida. Indianapolis, IN: Nature Publication Company.

DeCoursey, R., R. Allen. 1968. A generic key to the nymphs of the Pentatomidae of the eastern United States (Hemiptera: Heteroptera). University of Connecticut Occasional Papers (Biological Science Series), 1: 141-151.

Dietz, L., J. Van Duyn, J. Bradley, R. Rabb, W. Brooks, R. Stinner. 1976. A guide to the identification and biology of soybean arthropods in North Carolina. North Carolina Agricultural Experiment Station Technical Bulletin, 238: 1-264.

Eger, J., J. Ables. 1981. Parasitism of Pentatomidae by Tachinidae in South Carolina and Texas. Southwestern Entomologist, 6: 28-33.

Eisner, T., M. Eisner. 2000. Defensive use of a fecal thatch by a beetle larva (Hemisphaerota cyanea). Proceedings of the National Academy of Sciences, 97: 2632-2636.

Hayslip, N., W. Genung, E. Kelsheimer, J. Wilson. 1953. Insects attacking cabbage and other crucifers in Florida. University of Florida Agricultural Experiment Station Bulletin, 534: 1-57.

Howard, N., B. Landis. 1936. Parasites and predators of the Mexican bean beetle in the United States. U.S. Department of Agriculture Circular, 418: 1-12.

Kochansky, J., J. Aldrich, W. Lusby. 1989. Synthesis and pheromonal activity of 6,10,13-trimethyl-1-tetradeconal for predatory stink bug, Stiretrus anchorago (Heteroptera: Pentatomidae). Journal of Chemical Ecology, 15: 1717-1728.

McPherson, J. 1982. The Pentatomoidea (Hemiptera) of northeastern North America with emphasis on the fauna of Illinois. Carbondale, IL: Southern Illinois University Press.

McPherson, J., R. Mohlenbrock. 1976. A list of the Scutelleroidea of the La Rue-Pine Hills Ecological Area with notes on biology. Great Lakes Entomologist, 9: 125-169.

Millar, J. 2005. Pheromones of true bugs. Topics in Current Chemistry, 240: 37-84.

Oetting, R., T. Yonke. 1971. Immature stages and biology of Podisus placidus and Stiretrus fimbriatus (Hemiptera: Pentatomidae). Canadian Entomologist, 103: 1505-1516.

Rebagliati, P., L. Mola, A. Papeschi, J. Grazia. 2005. Cytogenetic studies in Pentatomidae (Heteroptera): A review. Journal of Zoological Systematics and Evolutionary Research, 43: 199-213.

Richman, D. 1977. Predation on the alfalfa weevil, Hypera postica (Gyllenhal), by Stiretrus anchorago (F.) (Hemiptera: Pentatomidae). Florida Entomologist, 60: 192.

Richman, D., F. Mead. 2008. "Predatory stink bug, Stiretrus anchorago (Fabricius) (Insecta: Hemiptera: Pentatomidae)" (On-line pdf). Accessed June 13, 2012 at edis.ifas.ufl.edu/pdffiles/IN/IN38600.pdf.

Richman, D., W. Whitcomb. 1978. Comparative life cycles of four species of predatory stink bugs. Florida Entomologist, 61: 113-119.

Scholtens, B. 1990. Pre-alighting host plant location in the Baltimore checkerspot butterfly, Euphydryas phaeton, and its implications for host range evolution in butterflies. Ann Arbor, MI: University of Michigan.

Staddon, B. 1979. The scent glands of Heteroptera. Advances in Insect Physiology, 14: 351-418.

Waddill, V., M. Shepard. 1975. A comparison of predation by the pentatomids, Podisus maculiventris (Say) and Stiretrus anchorago (F.), on the Mexican bean beetle, Epilachna varivestis Mulsant. Annals of the Entomological Society of America, 68: 1023-1027.

Waddill, V., M. Shepard. 1974. Biology of a predaceous stink bug, Stiretrus anchorago, (Hemiptera: Pentatomidae). Florida Entomologist, 57: 249-253.

 
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Scholtens, B. 2012. "Stiretrus anchorago" (On-line), Animal Diversity Web. Accessed August 29, 2014 at http://www.biokids.umich.edu/accounts/Stiretrus_anchorago/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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