Tetraopes tetrophthalmus

Geographic Range

Tetraopes tetrophthalmus, commonly known as red milkweed beetles, are native to the Nearctic. They are found in the northeastern part of North America. (Coin, et al., 2019)

Tetraopes tetrophthalmus, commonly known as red milkweed beetles, are found in the northeastern part of North America. (Coin, et al., 2019)


Red milkweed beetles are most commonly found near their host plant, common milkweeds. (Coin, et al., 2019)

Physical Description

Red milkweed beetles are 8-15 mm in length. They are narrow and elongated. They are reddish in color with symmetrical black spots. Their antennae are unridged. Larvae are pale in color. They are elongated and ridged. Depending on their primary food source, their sizes may differ. (Coin, et al., 2019)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    8 to 15 mm
    0.31 to 0.59 in


Red milkweed beetles go through instars of development. Larvae go through a few instars before pupating. They undergo metamorphosis in order to become adults.


Red milkweed beetles utilize internal fertilization and sexual reproduction. Females lay eggs on their host plants. Females select larger males for mating over the smaller males. (Mason, 1983)

Red milkweed beetles do not exhibit parental investment.

  • Parental Investment
  • no parental involvement


The lifespan of red milkweed beetles has not been determined.


Adult red milkweed beetles feed during June and July. They tend to be solitary. As fliers, red milkweed beetles are able to easily move around. (Mason, 1983)

Communication and Perception

Red milkweed beetles mostly communicate through pheromones. They use visual, tactile, and chemical senses of perception.

Food Habits

Red milkweed beetles feed primarily on the leaves, stems, and flowers of their host plant, common milkweeds. They have also been observed feeding on horsetail milkweeds. Those that feed on horsetail milkweeds tend to be smaller than those that feed on common milkweeds. Adults feed on foliage while larvae feed on roots. (Coin, et al., 2019; Mason, 1983)

  • Plant Foods
  • leaves
  • wood, bark, or stems
  • flowers

Ecosystem Roles

Red milkweed beetles impact the species of plants from which they feed.

Economic Importance for Humans: Negative

They can be household pests.

  • Negative Impacts
  • household pest

Conservation Status

Red milkweed beetles are not currently undergoing any conservation efforts.


Deena Hauze (author), Animal Diversity Web Staff.



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

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.


uses smells or other chemicals to communicate


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


union of egg and spermatozoan


an animal that mainly eats leaves.


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


An animal that eats mainly plants or parts of plants.


the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

internal fertilization

fertilization takes place within the female's body


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.


having the capacity to move from one place to another.


This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

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


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


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


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


lives alone


uses touch to communicate


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).

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.


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.


uses sight to communicate


Coin, P., B. Moisset, R. McLeod, M. Quinn. 2019. "Species Tetraopes tetrophthalmus - Red Milkweed Beetle" (On-line). Bug Guide. Accessed October 23, 2020 at https://bugguide.net/node/view/2966.

Erwin, A., T. Züst, J. Ali, A. Agrawal. 2014. Above-ground herbivory by red milkweed beetles facilitates above- and below-ground conspecific insects and reduces fruit production in common milkweed. Journal of Ecology, 102(4): 1038-1047. Accessed October 26, 2020 at https://www.jstor.org/stable/24541559.

Mason, L. 1983. Secondary Sexual Characteristics and Sexual Selection in Tetraopes. The American Midland Naturalist, 110(2): 235-239.

Matter, S. 2009. Abundance of an Herbivorous Beetle: Factors Affecting Dispersal and Local Reproduction. The American Midland Naturalist, 162(1): 19-28. Accessed October 26, 2020 at https://www.jstor.org/stable/25602294.

Price, P., M. Willson. 1976. Some Consequences for a Parasitic Herbivore, the Milkweed Longhorn Beetle, Tetraopes tetrophthalmus, of a Host-Plant Shift from Asdepias syriaca to A. verticillata. Oecologia, 24(4): 331-340. Accessed October 26, 2020 at https://www.jstor.org/stable/4215330.