''Oncopeltus fasciatus'', known as the large milkweed bug, is a medium-sized

hemiptera Hemiptera (; ) is an order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from ...

n (true bug) of the family

Lygaeidae The Lygaeidae are a family in the Hemiptera (true bugs), with more than 110 genera in four subfamilies. The family is commonly referred to as seed bugs, and less commonly, milkweed bugs, or ground bugs. Many species feed on seeds, some on sap or ...

.Attisano, A. (2013) Oosorption and migratory strategy of the milkweed bug,''Oncopeltus fasciatus. Animal Behaviour 86(3):651-657.'' It is distributed throughout

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, from

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

through

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

and the

Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...

to southern areas in

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

Costa Rica Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...

represents this insect's southern limit. It inhabits disturbed areas, roadsides, and open pastures.Dingle, H., Palmer, J.O., Leslie, J.F. (1986) Behaviour genetics of flexible life histories in milkweed bugs (''Onceopeltus fasciatus''). Evolutionary Genetics of Invertebrate Behavior. New York: Plenum Press. Due to this widespread geographic distribution, this insect exhibits varying life history trade-offs depending on the population location, including differences in wing length and other traits based on location.

Identification

Adults can range from 11 to 12 mm in length and have a red/orange and black X-shaped pattern on their wings underneath the triangle that is typical to hemipterans. This feature makes the bug easily seen, acting as an

aposematic Aposematism is the Advertising in biology, advertising by an animal, whether terrestrial or marine, to potential predation, predators that it is not worth attacking or eating. This unprofitability may consist of any defenses which make the pr ...

warning to predators of distastefulness. ''O. fasciatus'' exhibits

Müllerian mimicry Müllerian mimicry is a natural phenomenon in which two or more well-defended species, often foul-tasting and sharing common predators, have come to mimicry, mimic each other's honest signal, honest aposematism, warning signals, to their mutuali ...

and is noxious to predators. The ventral side of the fourth abdominal segment bears a black band in the male and two black spots in the female. Juveniles are born mostly red with black antennae and a few black spots, throughout growth the black spots are developed as well as wing pads. Eggs of this insect are bright orange and easily detectable.

Life cycle

Asclepias syriaca-Oncopeltus fasciatus-pod

This large milkweed bug is a

hemimetabolous Hemimetabolism or hemimetaboly, also called partial metamorphosis and paurometabolism,McGavin, George C. ''Essential Entomology: An Order-by-Order Introduction''. Oxford: Oxford University Press, 2001. pp. 20. is the mode of development of certain ...

insect, meaning it grows in stages called

instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...

s and goes through incomplete

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

, exhibiting small changes throughout development such as coloration changes, development of wings and genitalia. ''O. fasciatus'' begins as an egg and experiences four nymphal stages over 28–30 days before moulting to adulthood. Females become sexually receptive within a few days of adulthood. Geographic location has a large effect on egg production rate and clutch size, although the intrinsic increase in reproduction depends on to what the individual is acclimated. For example, two close populations (60 km apart) residing on a sharp incline have differing optimal reproduction temperatures, where the cooler (higher) adapted population is at 23 °C and the warmer (lower) population is adapted to 27 °C. Highest clutch size occurs in Puerto Rico, Florida, and Texas populations at 30-50 eggs per clutch. Lowest clutch size was found in California at 25-30 eggs per clutch. Iowa and Maryland (northern populations) exhibited a clutch size in between the two extremes from 25 to 35 eggs per clutch. In favourable conditions (

tropics The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

) reproduction occurs continuously all year round, in less-favourable conditions (

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

zones) reproduction occurs during the warmer months.Woodring, J., et al. (2007) Feeding, nutrient flow, and digestive enzyme release in the giant milkweed bug. ''Physiological Entomology'' 32:328-335. Reproducing when migrants arrive introduces

gene flow In population genetics, gene flow (also known as migration and allele flow) is the transfer of genetic variation, genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent ...

between northern and southern populations, this provides an advantage to the midrange populations (variable climates) because females then can ensure genetic variability. The milkweed bug can produce from one to three generations per year depending on climate and geographic location. ''O. fasciatus'' exhibits strong

selection Selection may refer to: Science * Selection (biology), also called natural selection, selection in evolution ** Sex selection, in genetics ** Mate selection, in mating ** Sexual selection in humans, in human sexuality ** Human mating strat ...

for survival and will halt reproduction as a trade-off if conditions are not ideal. Large Milkweed Bug

Diapause In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.Tauber, M.J., Tauber, C.A., Masaki, S. (1986) ''Seasonal Adaptations of Insects''. Oxford University Press It ...

occurs on short days and on cold days in temperate regions and occasionally occurs during dry season in tropical regions. Most populations of the milkweed bug overwinter, usually after migration to their overwintering sites due to environmental triggers such as temperature and

photoperiod Photoperiod is the change of day length around the seasons. The rotation of the earth around its axis produces 24 hour changes in light (day) and dark (night) cycles on earth. The length of the light and dark in each phase varies across the season ...

. However, photoperiod only predicts overwintering in areas where day length affects the maturation of milkweeds. Therefore, no overwintering occurs in tropical regions, as it does not supply an adaptive advantage.

Migration

Large Milkweed Bug Oncopeltus fasciatus Mating

''O. fasciatus'' can be separated into migrators and nonmigrators. Palmer and Dingle showed that northern populations such as the one in Iowa show the greatest tendency for long-distance flight and are highly migratory. Oppositely, southern populations such as those in Puerto Rico show the lowest tendency and are sedentary. Southern populations grow seasonally as migrants first appear in late spring and mid-summer. A migratory syndrome has been described in the northern population, meaning that traits such as wing length, fecundity, developmental time and flight duration are all genetically correlated. Groeters and Dingle suggested that selection is specific to the populations environment due to the small correlations between life-history strategies across geographic ranges. A

trade-off A trade-off (or tradeoff) is a situational decision that involves diminishing or losing on quality, quantity, or property of a set or design in return for gains in other aspects. In simple terms, a tradeoff is where one thing increases, and anoth ...

between migration and life history traits may be the causation of such a wide geological distribution. Attisano suggested that genetic factors as well as environmental cues trigger migration in some individuals. Since long duration flights decrease with decreasing latitude, temperature is a strong factor influencing the migration. Also, this movement correlates with

flowering Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

of milkweeds which provides further evidence that environmental triggers relate to migration. Larger females are thought to allocate resources to migration simply because they have more to spare. Smaller individuals are thought to deploy alternative mechanisms; one being the reabsorption of oocytes for energy. The fact that these insects return to northern environments after migration could be the influence of a

genetic predisposition Genetic predisposition refers to a genetic characteristic which influences the possible phenotypic development of an individual organism within a species or population under the influence of environmental conditions. The term genetic susceptibil ...

or selected for due to crowding and increased

intraspecific competition Intraspecific competition is an interaction in population ecology, whereby members of the same species compete for limited resources. This leads to a reduction in fitness for both individuals, but the more fit individual survives and is able to ...

for resources in the southern areas. Tropical populations migrate shorter distances than temperate populations because spatial variation of their choice host is much greater, so it is advantageous to seek new plant congregations rather than tolerate the depletion of resources.

Diet

''O. fasciatus'' is a specialist herbivore that frequently consumes

milkweed ''Asclepias'' is a genus of herbaceous, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are toxic to huma ...

seeds. In addition to its plant-based diet, O. fasciatus has been observed feeding on

aphid Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...

monarch A monarch () is a head of stateWebster's II New College Dictionary. "Monarch". Houghton Mifflin. Boston. 2001. p. 707. Life tenure, for life or until abdication, and therefore the head of state of a monarchy. A monarch may exercise the highest ...

caterpillar eggs, and larvae, displaying opportunistic behavior. This bug also feeds on '' A. nivea'', '' Sarcostemma clausa'', ''

Calotropis procera ''Calotropis procera'' is a species of flowering plant in the family Apocynaceae that is native to North Africa, Northern and Afrotropical realm, Tropical Africa, West Asia, Western Asia, South Asia and Mainland Southeast Asia, Indochina (main ...

'', and ''

Nerium oleander ''Nerium oleander'' ( ), commonly known as oleander or rosebay, is a shrub or small tree cultivated worldwide in temperate and subtropical areas as an ornamental and landscaping plant. It is the Monotypic taxon, only species currently classifi ...

''. The southern populations often consume ''Asclepias curassavica,'' a tropical milkweed. When given sunflower seeds in a laboratory, this bug obtained 90% of their lipids, 50% of their protein and 20% of their carbohydrates, making it an efficient feeder. Toxic compounds in milkweeds are also sequestered, giving this insect its toxicity. Adults wander during the daytime in search of food since milkweeds live in patches that can vary in size and distance apart from one another. When a follicle is found, they inject saliva into it through their long rostrums, this pre-digests the seed and allows ''O. fasciatus'' to suck it up through their anterior pump and pharynx. Often, multiple individuals feed on one follicle, suggesting that a signal is released by feeding individuals that indicates a good food source. It has been shown that adults are more likely to find a food source when another adult is already feeding on it, further supporting the signaling concept. Occasionally, females are seen feeding on shedding exoskeletons from moulting individuals. Rarely, cannibalization is observed in laboratory settings. Juveniles of ''O. fasciatus'' require the seed of milkweed plants for development and growth. Adults can survive on other types of seeds, such as sunflower, watermelon, almond, and cashew, as shown in lab populations. Nymphs live in large groups of about 20 individuals on the plant. Juveniles have a discontinuous, three-part gut that acts similarly to a crop, ventriculus, and

ileum The ileum () is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may ...

, but these are all three parts of the midgut, and there is no connection to the true ileum prior to the adult stage. During the final instar of development, oil accumulates, perhaps to allow for more efficient absorption of nutrients, aid in

osmoregulation Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration ...

or to preserve cleanliness of the habitat. It is expelled within 24 hours after the molt to adult, once a patent connection forms between the midgut and ileum.

Laboratory use

This insect is often used as a

model organism A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...

and reared for laboratory experiments due to being easy to rear and handle, short developmental time, few instars, and high

fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the capability to produc ...

.Liu, P., Kaufman, T.C. (2009) Morphology and husbandry of the large milkweed bug, ''Oncopeltus fasciatus''. ''Animal Behaviour'' 86(3): 651-657. The

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

placement of ''O. fasciatus'' is ideal to use as an

outgroup Outgroup may refer to: * Outgroup (cladistics), an evolutionary-history concept * Outgroup (sociology) In social psychology and sociology, an in-group is a social group to which a person psychologically identifies as being a member. By cont ...

to make comparisons to more derived

holometabolous Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphic trait of all insects in the clade Holometabola. Immatur ...

insects, acting as a valuable organism for the study of evolutionary patterns.

Gallery

File:Early instar milkweed bugs.webm, thumbtime=60, Early instar large milkweed bugs on

late in the season. File:Late instar adult milkweed bugs.webm, thumbtime=8, Late instar and adult large milkweed bugs on

late in the season. File:Milkweed bug flying.webm, thumbtime=17, Large milkweed bug

flying Flying may refer to: * Flight, the process of flying * Aviation, the creation and operation of aircraft Music Albums * '' Flying (Cody Fry album)'', 2017 * ''Flying'' (Grammatrain album), 1997 * ''Flying'' (Jonathan Fagerlund album), 2008 * ...

, repeated at one fifteenth speed File:Argiope and milkweedBug.webm, thumbtime=5, The banded orb weaving spider wraps up a

large milkweed bug ''Oncopeltus fasciatus'', known as the large milkweed bug, is a medium-sized hemipteran (true bug) of the family Lygaeidae.Attisano, A. (2013) Oosorption and migratory strategy of the milkweed bug,''Oncopeltus fasciatus. Animal Behaviour 86(3):65 ...

and subsequently cuts it from its web. This illustrates the protection the bug gained form feeding on

References

Migratory behavior
Roy L. Caldwell Mary Ann Rankin. Journal of comparative physiology. Separation of migratory from feeding and reproductive behavior in ''Oncopeltus fasciatus'' {{Authority control Lygaeidae Hemiptera of North America Insects described in 1852