Cremastocheilus maritimus

Distinguished from other Cremastocheilus by geographic range (coastal California) and subtle morphological differences described by Casey. Within its range, combination of small size (~10 mm), flattened angular body, dense pitted exoskeleton, and ant-associated behavior distinguishes it from other scarabs. Trichomes on pronotal hind angle visible with magnification. Death-feigning posture—motionless with legs outstretched—observed when disturbed in ant traffic areas.

Small scarab beetle, approximately 10 mm in body length. Body flattened and angular with dull black coloration. Exoskeleton dense, often with pits or wrinkles. Antennae normally protected in grooves under the head. Hind angle of pronotum bears trichomes—brushes of hairs attached to glands. Mentum enlarged and shield-like, covering other mouthparts from below. Maxillae modified into sharp appendages. Mandibles reduced.

Associated with ant nest mounds, particularly in coastal areas. Found in environments where host ants are active. Specific microhabitat preferences within California coastal zone not well documented.

Nearctic: coastal California, USA. Records from California represent the known range.

Adults disperse to find new hosts during spring. Newly emerged adults appear in late summer or fall. Life cycle from egg to adult approximately four months.

Adults feed on larvae and pupae of ants. Larvae feed on decaying vegetation composted by host ants.

• Formica - hostmound-building ants, primary hosts for genus
• Myrmecocystus - hosthoneypot ants, host for other Cremastocheilus species
• Lasius - hostcornfield ants, host for other Cremastocheilus species
• Camponotus - hostcarpenter ants, host for other Cremastocheilus species
• Pogonomyrmex - hostharvester ants, frequent hosts in southwestern species
• Veromessor - hostharvester ants, frequent hosts in southwestern species
• Aphaenogaster - hostspine-waisted ants, frequent hosts in southwestern species

Females lay eggs singly in soil around ant nest mound periphery. Larvae pass through three instars, feeding on decaying vegetation. Pupation occurs in oval chambers constructed from soil particles. Egg to adult development takes approximately four months. Newly emerged adults move to nest center, accumulating colony scent. Adults overwinter in ant nests, becoming active predators in spring.

Adults employ death-feigning (thanatosis) to gain entry to ant colonies: remain motionless with legs outstretched in areas trafficked by worker ants. Ants carry the apparently dead beetle into the nest. Newly emerged adults slowly migrate to nest center, acquiring colony odor. Larvae defend against ant attacks by striking with jaws and secreting repulsive liquids from mandibular and anal glands. Adults are fast, capable fliers but crash-land in ant-frequented areas.

Predator within ant colonies. Larvae contribute to decomposition of nest vegetation. As myrmecophile, represents specialized consumer of ant brood in ecosystem.

No direct economic significance. Of interest to entomologists studying myrmecophily and ant-beetle relationships. Rarely encountered by general public due to cryptic lifestyle within ant nests.

• Other Cremastocheilus speciesShare myrmecophilous lifestyle, death-feigning behavior, and morphological adaptations; distinguished by geographic distribution and subtle morphological characters
• Other Cetoniinae scarabsSimilar body form but lack myrmecophilous adaptations and ant association

• myrmecophile
• scarab beetle
• ant predator
• death-feigning
• California endemic
• Cetoniinae

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• Bug Eric: Anteater Scarab Beetles
• Ants invade Beetles in the Bush! | Beetles In The Bush
• a citizen scientist’s journey into botany