Home / Ground Beetles (Carabidae) / Fiery Searcher Beetle (Calosoma scrutator)

Fiery Searcher Beetle (Calosoma scrutator)

The fire searcher beetle is a member of the family of ground beetles. It is alternately called caterpillar hunter as it preys upon caterpillar in its larva and adult stage, helping to keep the pest population down. They secrete a foul-smelling oil, similar to rotten milk or rancid olive oil, when handled. These beetles, one of the largest ground beetle species, can fly but do so rarely. They are among the few species belonging to their genus that can climb trees and shrubs while foraging.

Fiery Searcher Beetle

Scientific Classification

  • Family: Carabidae
  • Genus: Calosoma
  • Scientific name: Calosoma scrutator

Physical Description and Identification

Adult

Size: 35 mm (1.4 in)

Color: Its wing covers are bright metallic green, with purple or reddish-gold margins. The head is black with brown jaws, its protonum is blue-violet, and its legs are dark blue-violet.

Other Characteristic Features: They have highly developed compound eyes and strong mandibles to manipulate food. Sexual dimorphism exists in these beetles, as the males have strongly curved, reddish setae, which the females do not.

Calosoma scrutator

Larva

Larvae are pale white when they emerge from their eggs. After an hour or two, they become darker. The dorsal region is dark brown, and the ventral portion is light brown. It goes through three instars, the first lasting for 3-6 days, the second for 4-7 days, and the third for 9-15 days. They start at 10 mm and end up at around 20-25 cm when fully mature.

Fiery Searcher Beetle Larva

Pupa

The pupa starts creamy white, later taking on the color of the adults. They pupate in the soil for 10-15 days.

Egg

These eggs are white with a tinge of yellow, 5mm long, 2mm wide, and oblong shaped, tapering off in the end.

Quick Facts

Other namesCaterpillar hunter beetle
Lifespan2 years
DistributionUnited States, Mexico, Guatemala, southern Canada, and Venezuela
HabitatFields, gardens, and deciduous forests
PredatorsToads, birds, foxes, skunks, raccoons, and shrews
Seasons activeMay to August
Diet of adults and larvaeCaterpillars

Identifying the Damage Caused by Them

Both the larvae and the adult are carnivorous and do no damage to any plants.

Did You Know

  • Danish zoologist Johan Christian Fabricius first described this species in 1775. 
Caterpillar Hunter Beetle
Fiery Searcher Beetle Range
Fiery Searcher Beetle Picture

Image Source: content.eol.org, entnemdept.ufl.edu, bugguide.net, researchgate.net, i.pinimg.com

The fire searcher beetle is a member of the family of ground beetles. It is alternately called caterpillar hunter as it preys upon caterpillar in its larva and adult stage, helping to keep the pest population down. They secrete a foul-smelling oil, similar to rotten milk or rancid olive oil, when handled. These beetles, one of the largest ground beetle species, can fly but do so rarely. They are among the few species belonging to their genus that can climb trees and shrubs while foraging.

Fiery Searcher Beetle

Physical Description and Identification

Adult

Size: 35 mm (1.4 in)

Color: Its wing covers are bright metallic green, with purple or reddish-gold margins. The head is black with brown jaws, its protonum is blue-violet, and its legs are dark blue-violet.

Other Characteristic Features: They have highly developed compound eyes and strong mandibles to manipulate food. Sexual dimorphism exists in these beetles, as the males have strongly curved, reddish setae, which the females do not.

Calosoma scrutator

Larva

Larvae are pale white when they emerge from their eggs. After an hour or two, they become darker. The dorsal region is dark brown, and the ventral portion is light brown. It goes through three instars, the first lasting for 3-6 days, the second for 4-7 days, and the third for 9-15 days. They start at 10 mm and end up at around 20-25 cm when fully mature.

Fiery Searcher Beetle Larva

Pupa

The pupa starts creamy white, later taking on the color of the adults. They pupate in the soil for 10-15 days.

Egg

These eggs are white with a tinge of yellow, 5mm long, 2mm wide, and oblong shaped, tapering off in the end.

Quick Facts

Other namesCaterpillar hunter beetle
Lifespan2 years
DistributionUnited States, Mexico, Guatemala, southern Canada, and Venezuela
HabitatFields, gardens, and deciduous forests
PredatorsToads, birds, foxes, skunks, raccoons, and shrews
Seasons activeMay to August
Diet of adults and larvaeCaterpillars

Identifying the Damage Caused by Them

Both the larvae and the adult are carnivorous and do no damage to any plants.

Did You Know

  • Danish zoologist Johan Christian Fabricius first described this species in 1775. 
Caterpillar Hunter Beetle
Fiery Searcher Beetle Range
Fiery Searcher Beetle Picture

Image Source: content.eol.org, entnemdept.ufl.edu, bugguide.net, researchgate.net, i.pinimg.com

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