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Cactus Longhorn Beetle (Moneilema)

The cactus longhorn beetles are a genus belonging to the family of longhorn beetles. These beetles are found in North American deserts, with both the adults and the larvae feeding on cacti.

The most well known species of this genus is Moneilema gigas, which is a flightless, black beetle found in the Sonoran desert.

Cactus Longhorn Beetle

List of Species Belonging to this Genus

  • Moneilema albopictum
  • Moneilema annulatum
  • Moneilema appressum
  • Moneilema armatum
  • Moneilema aterrimum
  • Moneilema blapsides
  • Moneilema crassipes
  • Moneilema ebeninum
  • Moneilema gigas
  • Moneilema longipes
  • Moneilema manni
  • Moneilema mexicanum
  • Moneilema michelbacheri
  • Moneilema opuntiae
  • Moneilema punctipennis
  • Moneilema rugosissimum
  • Cactus Borer Beetle (Moneilema semipunctatum)
  • Moneilema subrugosum
  • Moneilema variolare
  • Moneilema wickhami
Cactus Longhorn Beetle Image

Physical Description and Identification

Adult 

Size: 0.51-1.46 in (1.3-3.7 cm)

Color: They are mostly black, with mottled white elytra.

Other Characteristic Features: These beetles are incapable of flight, with their elytra fusing into a single, hardened shell. Their head is elongated, almost horse-like.

Moneilema

Larva

The larvae have brown heads and can be found inside the stem or roots of their host plants.

Cactus Longhorn Beetle Larva

Pupa

Pupation occurs inside the cactus they fed on as a larva, overwintering during this period.

Egg

The eggs are laid in different parts of the cactus by the female beetle.

Quick Facts

Lifespan1-2 year
DistributionWestern United States and northern Mexico
HabitatArid and semi-arid regions such as deserts
PredatorsLizards, skunks, and wood rats
Seasons activeMay-September
Host PlantsCacti, mainly prickly pear and cholla
Diet of adultsFlowers, fruits, and foliage of cacti
Longhorn Cactus Beetle

Identifying the Damage Caused by Them

The larva bore into cacti, causing damage to their roots and stems. While burrowing in, they secrete a green substance that hardens and turns black. This substance damages the cactus, softening its tissue.

Cactus Longhorn Beetle Picture

Did You Know

  • American entomologist Thomas Say first described this genus in 1824.

Image Source: content.eol.org,live.staticflickr.com, i.pinimg.com, angelfire.com, a4.pbase.com, wixmp.com

The cactus longhorn beetles are a genus belonging to the family of longhorn beetles. These beetles are found in North American deserts, with both the adults and the larvae feeding on cacti.

The most well known species of this genus is Moneilema gigas, which is a flightless, black beetle found in the Sonoran desert.

Cactus Longhorn Beetle

List of Species Belonging to this Genus

  • Moneilema albopictum
  • Moneilema annulatum
  • Moneilema appressum
  • Moneilema armatum
  • Moneilema aterrimum
  • Moneilema blapsides
  • Moneilema crassipes
  • Moneilema ebeninum
  • Moneilema gigas
  • Moneilema longipes
  • Moneilema manni
  • Moneilema mexicanum
  • Moneilema michelbacheri
  • Moneilema opuntiae
  • Moneilema punctipennis
  • Moneilema rugosissimum
  • Cactus Borer Beetle (Moneilema semipunctatum)
  • Moneilema subrugosum
  • Moneilema variolare
  • Moneilema wickhami
Cactus Longhorn Beetle Image

Physical Description and Identification

Adult 

Size: 0.51-1.46 in (1.3-3.7 cm)

Color: They are mostly black, with mottled white elytra.

Other Characteristic Features: These beetles are incapable of flight, with their elytra fusing into a single, hardened shell. Their head is elongated, almost horse-like.

Moneilema

Larva

The larvae have brown heads and can be found inside the stem or roots of their host plants.

Cactus Longhorn Beetle Larva

Pupa

Pupation occurs inside the cactus they fed on as a larva, overwintering during this period.

Egg

The eggs are laid in different parts of the cactus by the female beetle.

Quick Facts

Lifespan1-2 year
DistributionWestern United States and northern Mexico
HabitatArid and semi-arid regions such as deserts
PredatorsLizards, skunks, and wood rats
Seasons activeMay-September
Host PlantsCacti, mainly prickly pear and cholla
Diet of adultsFlowers, fruits, and foliage of cacti
Longhorn Cactus Beetle

Identifying the Damage Caused by Them

The larva bore into cacti, causing damage to their roots and stems. While burrowing in, they secrete a green substance that hardens and turns black. This substance damages the cactus, softening its tissue.

Cactus Longhorn Beetle Picture

Did You Know

  • American entomologist Thomas Say first described this genus in 1824.

Image Source: content.eol.org,live.staticflickr.com, i.pinimg.com, angelfire.com, a4.pbase.com, wixmp.com

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