Lucanus mazama

Geographic Range

Lucanus mazama , commonly known as the Cottonwood stag beetle, are found in North America, primarily in the southwest United States and southern Mexico.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Cottonwood stag beetles prefer dry, temperate to hotter habitats with loose soil and decaying wood. Ideal habitat for the species is woodland areas, particularly cottonwood forests in riparian areas. Recently they have been found in wood chip beds at urban parks and playgrounds.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• scrub forest scrub forest

• Other Habitat Features
• urban urban
• suburban suburban
• riparian riparian

Physical Description

This species is a type of stag beetle, with a mature segmented body, six legs, and a pair of clubbed antennae. They are most well known for their protruding front mandibles, which are longer and more prominent in males. They have compound eyes and flight wings hidden under hardened outer wings. Overall they range from a black to a dark brown color. They grow from 8 to 41 mm, with males being larger than females. In their larval phase, they are white with 6 orange legs, an orange head capsule, and a brown jaw. They turn yellow between each molt.

• Other Physical Features
• heterothermic heterothermic

• Sexual Dimorphism
• male larger
• ornamentation ornamentation

Development

The majority of this species life is spent underground in the larval stages. They can stay in their larval stages for multiple years, going through three instars. Once the larvae are fully grown, they will create a cocoon where they will pupate and metamorphosis into their adult form. This pupation can last up to 7 months to complete. Once complete, they will emerge from the soil in their adult form to mate, usually around mid-May, and will die by August.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

These beetles breed in the summer, May through August, when they are in their full adult form. Males will fly around at night searching for a mate. Once a male has found a mate, he will open up his mandibles and walk around her, showing himself off. If there is more than one male around a female, the males will fight each other with their mandibles until one falls onto its back to admit defeat. Males can have multiple mates and will even try to mate with dead females. Once a mate has been chosen, the male will climb on top of the female and enclose her with his mandibles. The female will then find dead or rotting wood to lay her eggs.

• Mating System
• polygynous polygynous

Cottonwood stag beetles mate during the summer season, usually May through August. After fertilization females will find rotting wood where they will create a hollow near soil to lay eggs. Females will usually lay 10 to 14 eggs. Eggs will hatch 3 weeks after being laid. Offspring are independent at birth as adults die after the breeding season. Larva will then spend the majority of their lives underground, going through multiple instars. They may stay underground for multiple years until metamorphosis into an adult. This usually takes two years, but has been recorded to take up to seven. Once an adult, they have reached sexual maturity and will emerge from the soil in summer to mate and then die.

• Key Reproductive Features
• semelparous semelparous
• seasonal breeding seasonal breeding
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Post fertilization, females will spend time creating a nursery to lay their eggs. They may dig around, chew up rotting wood and compacting it to create a hollow to lay her eggs in. After laying her eggs, the female will die. After the breeding season both male and female die and parental investment ends.

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

Lifespan/Longevity

Cottonwood stag beetles spend the majority of their life underground. It can take up to 7 years to reach sexual maturity as an adult and emerge aboveground. Periods of cold weather can extend the larval phase. Once aboveground, they only live for 3 to 6 weeks to breed and then die.

Behavior

There is not much research done on stag beetle behavior in general, especially for Lucanus mazama . They are a solitary species, although larvae may live in birth colonies underground as they mature. Social behaviors are found during the breeding season, which are often displays of aggression between males as they fight over females. During the day they usually sun themselves as they prepare for dusk, when they will fly around and look for a mate.

• Key Behaviors
• terricolous
• flies
• nocturnal nocturnal
• motile motile

Communication and Perception

Larva do not have any eyes and communicate through vibrations. Larva communicate through stridulation as they rub claws from their hind legs onto ridges on their middle legs. Adults have compound eyes and will also communicate through stridulation. Adults will also put on displays of aggression with their mandibles to impress females.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Other Communication Modes
• vibrations vibrations

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations

Food Habits

Cottonwood stag beetles do the majority of their eating in the larval stages. They eat dead wood and wood rot. As an adult they no longer can eat solid food and rely on fat reserves from their larval stages. Adults may use their tongue to drink sap or to drink from soft fruit. This species is herbivorous.

• Primary Diet
• herbivore herbivore
  • frugivore frugivore
  • lignivore
  • eats sap or other plant foods
• mycophage mycophage

• Plant Foods
• leaves
• wood, bark, or stems
• fruit
• sap or other plant fluids

• Other Foods
• fungus

Predation

Predators of Lucanus mazama include mammals such as cat and fox, birds such as kestrels and crows, and reptiles. Cottonwood stag beetles' enlarged mandibles work as a predator defense and when the beetle feels threatened it will lift its head and open up its mandibles to protect itself.

Ecosystem Roles

In their larval form, Lucanus mazama help to break down and decompose dead and rotting wood. As dead wood is their main diet, they help in the biodegradation process of dead vegetation.

• Ecosystem Impact
• biodegradation biodegradation

Economic Importance for Humans: Positive

Having this insect in your garden can be helpful as they will decompose dead vegetation for you. As they only consume dead wood, they will not harm any of your live plants or negatively impact your landscaping. Some people also keep stag beetles as pets.

• Positive Impacts
• produces fertilizer

Economic Importance for Humans: Negative

Humans may be intimidated by their long mandibles thinking that they may bite people or destroy peoples gardens, but L. mazama is very harmless. Mandibles are used to attract mates, not for biting. As they only feed on dead material they will not be disruptive in your garden.

Conservation Status

Cottonwood Stag Beetles do not have any special conservation status.

Other Comments

There has not been a lot of research done on this species. For stag beetles in general, and in particular for Lucanus mazama , there is little information on its life history. There is definitely more research that needs to be done on this species.

Additional Links

Encyclopedia of Life

Contributors

Claire Labuda (author), Colorado State University.

References

Kim, J., V. ANTOINE BROU. 2021. THE FAMILY LUCANIDAE LATREILLE, 1804 (COLEOPTERA) IN LOUISIANA. SOUTHERN LEPIDOPTERISTS’ NEWS , VOLUME 43 NO. 4: 371. Accessed August 21, 2023 at https://d1wqtxts1xzle7.cloudfront.net/79649780/The_Family_Lucanidae_Latreille_1804_Coleoptera_in_Louisiana._version_11_180_2021_proof_-libre.pdf?1643289902=&response-content-disposition=inline%3B+filename%3DTHE_FAMILY_LUCANIDAE_LATREILLE_1804_COLE.pdf&Expires=1692645047&Signature=fKP-c7JOLlNttDZzOzprg85uhswVYlH5PotcEkr5562tdnySjFImCAyq~n6oeGaazYNPt1DO79HfPLD1cUSPl7N88Nkn4cAYAVhf5vytPHh836f-s0jtr9tml~8lnHJbw8-9rqoUeW9rFNVbgqCK1HB9rNoAWBCoWQgw2Pz6yu2Q3Wh4c1SXLQvhztZl0IhfAkSezeMfFGuku4ujYVYsw4v5DJqILz1zW51DoR0d7yibxuQ5ftlT4tV2SMQlqZ00vRutdIQzD63Vy74CfodTyK4oHQuE1M83asuU7iuO0YzvRFeYCFwHUBUeu1Mvhkx~8Gw3fpoJzZlCpGOB-cn0KA__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA .

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Tikkanen, A. 2015. "Stag beetle" (On-line). Britannica. Accessed August 23, 2023 at https://www.britannica.com/animal/stag-beetle .

2023. "Cottonweed Stag Beetle (Lucanus mazama)" (On-line). Beetle Identifications. Accessed August 23, 2023 at https://beetleidentifications.com/cottonwood-stag-beetle/ .

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