Pest profile

Lilac Root Weevil

Otiorhynchus meridionalis · Coleoptera: Curculionidae[2]

Lilac root weevil adults chew angular notches in the leaves of lilac, privet, peony and euonymus at night.[1]

Lilac root weevil, a dark gray snout beetle with ridged wing covers, on a leaf
Lilac root weevil, a dark gray snout beetle with ridged wing covers, on a leaf. (c) antimatterbee, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are flightless, night-active snout beetles that hide by day around the base of plants.[1]
  • Leaf edges show distinctive angular notches; larvae are cream-colored legless grubs on the roots.[1]

Look-alikes

Look-alikeHow to tell them apart
Strawberry root weevilA relative with a much wider host range that often wanders indoors.[1]
Black vine weevilAnother relative, common on euonymus, heuchera, astilbe and hosta.[1]

Where it lives

It's one of the most common root weevils in Colorado.[1]

US map: public records from 14 states since 1990 (GBIF).

Biology and life cycle

Unlike strawberry root weevil, it produces both males and females; there's one generation a year.[1]

Larvae overwinter in soil, and adults emerge in mid to late spring; eggs are squeezed into soil cracks in late spring and early summer.[1]

Damage and signs

  • Leaf notching is the only easily seen injury; larvae feed on roots.[1]

Health risk

It feeds on plants; CSU Extension mentions no risk to people.[1]

Control

Traps and physical control

Look on plants at night to confirm which root weevil is present.[1]

Biological control

Heterorhabditis nematodes in moist, warm soil after egg hatch control the larvae.[1]

Pesticides

Pyrethroids on the lower trunk and base kill climbing adults; don't spray flowers that pollinators visit.[1]

Common questions

What's notching my lilac leaves?
Lilac root weevil adults feeding at night cut angular notches in leaf edges.[1]
Can lilac root weevils fly?
No; root weevils can't fly and crawl up plants after dark.[1]

Sources

  1. Colorado State University Extension, “Root Weevils (Fact Sheet 5.551).” extension.colostate.edu/resource/root-weevils/ (accessed 2026-10-06)
  2. iNaturalist, “Otiorhynchus meridionalis taxon page (order and family).” www.inaturalist.org/taxa/503271 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.