Essential oils: Will they kill biting midges?

Authors: Cohnstaedt, Lee

Submitted to: North American Deer Farmer
Publication Type: Trade Journal
Publication Acceptance Date: 10/20/2017
Publication Date: 12/1/2017
Citation: Cohnstaedt, L.W. 2017. Essential oils: Will they kill biting midges?. North American Deer Farmer. |https://doi.org/10.1111/j.1365-2915.2008.00743.x.
DOI: https://doi.org/10.1111/j.1365-2915.2008.00743.x

Interpretive Summary: Many individuals are concerned about insecticide products which leads to use of natural products. In this trade publication, natural products were tested to determine if were able to kill biting midges. The adult midges were fed toxic sugar containing the natural products. The midges were then held for up to 96 hours to see if there were delays in the mortality. This work on insecticidal sugar baits builds upon prior publications with insecticides dissolved in the sugar solutions which caused significant damage. In this case the essential oils that were tested were: boric acid, methyl eugenol, rosemary oil, peppermint, garlic oil, cinnamon, and sesame oil in 20% sugar solutions. None of the natural products killed midges.

Technical Abstract: Biting midge mortality when consuming solutions of boric acid, methyl eugenol, rosemary oil, peppermint, garlic oil, cinnamon, and sesame oil in 20% sugar solutions was assessed using colonized biting midges. The midges were fed up to 3% active ingredient (the essential oils or natural products) and held for up to 96 hours. Consumption of the natural products in the sugar solutions did not result in high biting midge mortality, even after 96 hours. This is in contrast to high mortality in biting midges from consumption of synthetic products in less than 24 hours. Mosquitoes tested as controls during these trials did have high mortality after 48-72 hours. The insecticidal sugar solutions were dyed and colored abdomens in the biting midges would confirm consumption of the toxic sugars despite low mortality. The essential oils and natural products in the sugar solution did not deter the biting midges from feeding on the solutions and none died from contact with the active ingredients as seen by low mortality at 24 hours but all the insect abdomens having some degree of color. Therefore we conclude that biting midges are much harder to kill than mosquitoes and much less susceptible to the natural products and essential oils. Furthermore, the essential oils and natural products did not repel the insects or prevent them from feeding on the sugar solution (repellent effects) even when a pure sugar (no toxin) was present.