Alydus eurinus

Geographic Range

Members of Alydus eurinus are broad-headed bugs (the common name for the entire family) native to North America. They have been found in 43 of the 50 states in the United States. These bugs are found across the entire continental United States from coast to coast and have been found as far south as Texas and Florida. Their range extends northward into Alaska and all 10 provinces of Canada. These insects also inhabit the Yukon Territory of Canada. (Swanson, 2018)


Alydus eurinus is found in many legume fields. Both adults and nymphs can be found on soybeans (Glycine max). They can also be found on wild legumes such as patches of crimson clover (Trifolium incarnatum) in fallow grasslands. These true bugs do not move far beyond these fields. (Schaefer, 1980; Underhill, 1943)

Physical Description

Broad-headed bugs (Alydus eurinus) can exist as an egg, a nymph and an adult. The eggs are less than 1mm in width and about 1mm in length. In their nymph stage, these true bugs are ant mimics. These bug possess has three major sections: the head, thorax and abdomen, with their six legs are attached to the thorax. The legs are very thin compared to the rest of the body. The legs articulate in two places, dividing them up into three sections. Their abdomen is shaped like an oval.

The nymph stage is divided up into 5 instars of growth. In the first instar they are 2.25-2.75mm in length. By the fifth instar, these bugs are ca. 7-11mm long. As adults, they mimic spider wasps (members of the family Pompilidae) with black bodies and orange under the wings. They have two sets of wings and when they are not flying the wings are closed on the back. Their adult legs are slightly thicker than their nymph legs in the first section. These larger sections have small spines that stick backwards from the leg.

The adults are about 10-14mm long. Adults have broad heads as their name would suggest, about the width of their thorax. Their compound eyes also stick out to the side of their head. Members of Alydus eurinus are true bugs, which means they possess piercing sucking mouthparts to feed. Adults are usually black but they can be lighter or almost brown in color. (Aldrich, et al., 2000; Clem and Charles, 2016; Underhill, 1943)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    10 to 14 mm
    0.39 to 0.55 in


Members of Alydus eurinus have 5 stages as a nymph called instars. Each instar lasts for 2.78 days on average. Between each instar, individuals molts their exoskeleton to allow for more growth. Females and males reach sexual maturity at 13.9 days after hatching on average. Eggs under short day conditions eggs have been observed to enter diapause until conditions are more favorable. Members of Alydus eurinus overwinter as eggs. (Musolin, et al., 1999; Panizzi, 1987)


Females of Alydus euriunus use a pheromone containing 2-methylbutyl butyrate and (E)-2-methyl-2-butenyl butyrate to attract males. Both sexes have striations on their hind femur that allows for the production of sound. This sound can only be heard from a few centimeters away but allows for individual pairs to separate from other individuals within the species. Females and males are polygynandrous, meaning they have multiple mates. They use internal fertilization for reproduction. (Aldrich, et al., 2000; Yonke and Medler, 1968)

The breeding for broad-headed bugs occurs between the months of April and August. Females can lay up to ten eggs five times per breeding season. The average number of eggs produced per season is 27. Eggs take 2.4 to 2.9 days to incubate. Time to independence is zero days, as parents provide no care post egg-laying or mating. Individuals of Alydus eurinus have 5 stages as a nymph called instars. Each instar lasts for 2.78 days, on average. Females and males reach sexual maturity ca. 13.9 days after hatching, on average. Females live for up to 180 days, though the average of 66.8 days is significantly shorter. Males live up to 176 days with the average being 76.1 days. These lifespans suggest they are semelparous - breeding for one season or effort and then dying. (Aldrich, et al., 2000; Underhill, 1943; Yonke and Medler, 1968)

  • Breeding interval
    Members of Alydus eurinus breed up to five times laying up to ten eggs per mating.
  • Breeding season
    Breeding occurs between the months of April and August
  • Range eggs per season
    50 (high)
  • Average eggs per season
  • Range time to independence
    0 to 0 minutes
  • Average age at sexual or reproductive maturity (female)
    13.9 days
  • Average age at sexual or reproductive maturity (male)
    13.9 days

After laying eggs, females have no involvement with their young after ovipositing. Males exhibit no parental investment beyond the act of mating. (Panizzi, 1987)

  • Parental Investment
  • no parental involvement


Members of Alydus eurinus have been observed in captivity to have female lifespans averaging 66.8 days (range 28 to 180 days) and male lifespans averaging 76.1 days (range 38 to 175 days). Members of Alydus eurinus have not be observed for longevity in the wild. (Yonke and Medler, 1968)

  • Range lifespan
    Status: captivity
    28 to 180 days
  • Typical lifespan
    Status: captivity
    66.8 to 76.1 days


Individuals of Alydus eurinus spends most of their time in solitude. They aggregate to feed and mate. Breeding and egg-laying occurs on the stems and pods of legumes. Nymphs and adults move from on legumes into leaf litter to hide from predators. Adults have wings to allow them to move around to feed or find mates (Schaefer, 1980; Underhill, 1943)

  • Range territory size
    0 (low) cm^2

Home Range

Not reported

Communication and Perception

Broad headed bugs (Alydus eurinus) use pheromones to attract mates. These pheromones are produced by females and attract males, and sometimes other females. They excrete these pheromones from a metathoracic scent gland. These true bugs attract mates by stridulation (producing sound by rubbing body parts together). The sound produced in this way can only be observed from a few centimeters away, indicating it is not effective over long distances. Individuals of Alydus eurinus have large compound eyes to see. They have antennae that help them feel their surroundings, detect pheromones and changes in temperature. (Aldrich, et al., 2000)

Food Habits

Members of Alydus eurinus feed primarily on legumes. These broad-headed bugs are commonly found on commercially-grown legumes including soybeans (Glycine max) and crimson clover (Trifolium incarnatum). They use their piercing sucking mouthparts to suck out the fluid in a seed or leaf. In this way, these bugs are folivores and granivores. Individuals of Alydus eurinus aggregate together when it feeds. It has also been found on carrion and feces but it is not a significant portion of its diet. (Clem and Charles, 2016; Schaefer, 1980; Underhill, 1943)

  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • Other Foods
  • dung


Instars of Alydus eurinus mimic ants (members of the family Formicidae), while adults mimics spider wasps (members of the family Pompilidae). Birds who frequent their habitats will opportunistically prey on these insects in its habitat. Spiders (Araneae) and other insects (Insecta) will eat them. Nymphs and adults move from on legumes into leaf litter to hide from predators. (Evans, 1964)

  • Anti-predator Adaptations
  • mimic

Ecosystem Roles

Individuals of Alydus eurinus consume nutrient rich fluids from the seeds and leaves of the plants in the family Fabaceae. This feeding does not directly kill the plant but does reduce productivity and yield in a commercial setting. Birds, spiders, and predatory insects prey on Alydus eurinus. Immature parasitic nematodes in the genus Hexamermis have been found on females of this species. (Evans, 1964; Schaefer, 1980; Underhill, 1943; Yonke and Medler, 1968)

Species Used as Host
  • Fabaceae
Commensal/Parasitic Species
  • Nematodes (Hexamermis)

Economic Importance for Humans: Positive

There are no known positive economic effects of Alydus eurinus on humans.

Economic Importance for Humans: Negative

Members of Alydus eurinus cause significant damage to commercial legume crops such as soybeans (Glycine max). They damage the pods and leaves reducing yield and marketability. (Schaefer, 1980; Underhill, 1943)

  • Negative Impacts
  • crop pest

Conservation Status

Members of Alydus eurinus have not been evaluated for the IUCN Red List. They have no special status on the CITES appendices, the United States endangered species list or the State of Michigan List.

Two threats to the species would be human use of insecticides to remove them from fields and predation.

Conservation efforts are not in place for this pest species. However, anti-conservation efforts are in place in areas where they damage legume crops. Insecticides are used such as pyrethroids to control them. (Schaefer, 1980; Underhill, 1943)


Brian Currin (author), Radford University, Logan Platt (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.



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


uses sound to communicate


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.


an animal that mainly eats meat


flesh of dead animals.


uses smells or other chemicals to communicate


an animal that mainly eats the dung of other animals


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.


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.


an animal that mainly eats seeds


An animal that eats mainly plants or parts of plants.

internal fertilization

fertilization takes place within the female's body


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.


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


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


an animal that mainly eats dead animals

seasonal breeding

breeding is confined to a particular season


remains in the same area


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.


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.


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate


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