To find this yellow-and-blue beetle, head for a wet forest edge in the eastern U.S. or in southeastern Canada. Then find an elderberry shrub, which has berries that ripen in late summer. Elderberry longhorn beetles are specialists: they rely on just this one host plant. The larvae eat only elderberry wood. The adult beetles gather pollen from flowers, including elderberry, and mate on or near the plants. And they may also gain toxicity by ingesting the plant, which can be toxic, too.

The fate of these insects is entwined with the populations of the plant it relies on, but as is common with many insects (and plants), we don’t know for certain how robust they are. In parts of the northeastern U.S., the beetles are declining, but elsewhere in their range, their status is unknown. For now, studies here and there bring a bit of positive news. Once officially endangered in Massachusetts, this beetle was removed from that state’s list after a new survey located many more of the iridescent insects.

Elderberry longhorn beetle
Desmocerus palliatus
0.7–1 inch (18–26 mm)
Imperiled (massachusetts, u.s.); vulnerable (new brunswick, canada) (natureserve)
Ecological Role
AMNH Specimen Number
AMNH_IZC 00292130
Massachusetts, U.S.