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Scentless chamomile (Tripleurospermum perforata) is a noxious weed that spreads readily throughout disturbed sites by way of massive seed production – up to one million seeds per plant! To help combat this weed, two insect biological control agents have been introduced in the Grande Prairie area.

 Scentless Chamomile Seed Weevil 

Scentless Chamomile Seed Weevil
(Omphalapion hookeri)

This insect is released in early summer onto flowering scentless chamomile plants. The adults disperse and lay their eggs in seedheads. When the larvae hatch, they eat the developing seeds.

The City of Grande Prairie conducts releases each year to help establish a stable population. It can take 5-10 years for a weevil population to become self-sustaining in an area.

  

Scentless Chamomile Gall Midge

 

Scentless Chamomile Gall Midge
(Rhopalomyia tripleurospermi)

These tiny, delicate flies lay their eggs in the growing points of chamomile plants. When the larvae hatch and begin feeding, they cause a disfiguring gall to form, disrupting the plant’s growth cycle and reducing flowering.

These insects are well established in the Grande Prairie area and galled plants can be found in most scentless chamomile populations.

Last updated: 12/5/2012 8:55:02 AM