MOSQUITO PLANT

by Liz Forsyth

P.T. Barnum may or may not have noted the birth of 60 suckers every hour, but even in the plant world, if it sounds too good to be true, it probably is.

In 2006, The International Herb Association designated scented geraniums as their Herb of the Year. A specific geranium, the Pelargonium citrosum ‘Van Leenii’, was touted in major articles, including the New York Times, as a wonder plant that kept yards mosquito-free. Claimed to be a revolutionary new breakthrough from a Dutch horticulturist, Mr. Van Leenen, it was genetically created by crossing tissue cultures of an African Geranium with the Grass of China. His claim was that the grass contained citronella oil, the active repellent ingredient, and that the geranium gave it the ability to effectively repel black flies and most biting insects. Mr. Van Leenen also claimed that it eliminated the need for aerosol sprays, thus helping the environment, and had the added plus of not being a greasy chemical lotion on your skin.

Ah, but not everyone bought into Mr. Van Leenen’s claims. A recent scientific paper published in the Journal of the American Mosquito Control Association debunks all claims made for Pelargonium citrosum, and suggested that the geranium, often sold at astronomical prices as a natural mosquito repellent, is merely a common rose-scented variety. And Dr. G.A. Surgeoner and J. Heal from the University of Guelph in Ontario tested both the effectiveness of ‘Citrosa’ and lemon thyme (thymus x citriodorus) against the biting activity of Aedes aegypti mosquitoes; their findings? There was no evidence of significant protection against mosquito bites.

Surgeoner and Heal found that if one crushed the leaves of ‘Citrosa” on the hand, it would produce an approximate 30-40% repellency. Crushed lemon thyme produced a 62% repellency. But the most effective product? The commercial Deep Woods Off produced a 90.4% reduction in biting activity.

There are several other plants that, when you rub their essential oils on yourself as an insect repellent, provide a natural, homemade option to the chemical sprays. However, you will need to apply frequently, as often as every 15 minutes. And while they may provide protection while you are dining out on the patio, or working around the yard, they are not recommended for hiking in the woods or kayaking!

Lest we have lead you to believe that the Pelargonium citrosum ‘Van Leenii’ is a useless plant, it is an ideal annual with lavender flowers that will grow to about 2 feet. It likes well-drained soil, good air circulation, and exposure to full sun of 6 to 8 hours a day. Plant it near a path so that the fragrance is released when someone walks by and brushes against the leaves. Or hang it on your patio or sun porch, and bring out the fragrance by rubbing the leaves. Even plants like a good massage!