Trilobite Beetle vs Elm Seed Bug

Side-by-side species comparison

Attribute Trilobite Beetle Elm Seed Bug
Scientific Name Duliticola hoiseni Arocatus melanocephalus
Order Coleoptera Hemiptera
Family Lycidae Lygaeidae
Size 40-80 mm (females), 8-10 mm (males) 6-7 mm
Habitat Underground Underground
Diet Fungus Feeders Seed Feeders
Regions Asia Europe (native), Northwestern North America (invasive)
Conservation Data Deficient Least Concern

Trilobite Beetle

Females are large, larviform, and look strikingly like trilobites from the Paleozoic era. Males are tiny conventional-looking beetles. One of the most extreme sexual dimorphisms in insects.

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Did You Know?

Females of this beetle retain their larval form throughout life and look like extinct trilobites — males are tiny normal beetles, creating one of natures most extreme sex differences.

Elm Seed Bug

A small seed bug native to southern Europe that has become an invasive nuisance pest in the northwestern United States. It aggregates in enormous numbers on and inside buildings in summer and fall.

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Did You Know?

Thousands can invade a single home seeking shelter, producing a foul odor when disturbed or crushed.