The Plant Man column for publication the week of 05/30/04 - 06/05/04 (775 words)
The Plant Man by Steve Jones
Evict mosquitoes from your landscape this summer!
Mosquitoes. Just hearing that word is enough to bring a scowl to the face of most people who spend time working on their garden or landscape. Not to mention a few choice cuss words!
In recent columns, I've talked about the benefits of rain gardens and water gardens, but with any water feature there's the possibility of providing
habitat for those pesky skeeters. In fact, with an increased awareness of West Nile Virus (or "West Vile Nirus" as I heard an NPR news anchor say it) the presence of mosquitoes can upgrade from "pesky" to "deadly."
Are there ways to reduce the presence of mosquitoes on your property? What about those so-called "mosquito plants?" I think it's time for a Plant Man Q & A!
Q: What's number one best way to decrease the number of mosquitoes?
A: Eliminate as many sources of standing water as possible. Trash can lids and buckets left lying around will quickly become mosquito breeding grounds after a rainfall. But also be on the lookout for tarps that can provide the perfect location for a cosy breeding puddle. The same goes for abandoned car tires and anything where standing water can form. The key word there is "standing." Just as a fast-moving stream is less likely to harbor mosquito larvae than a stagnant pond, a swimming pool or water garden (where water is kept fresh and moving with a circulating pump) will be "safer" than a wheelbarrow containing just a gallon or two of stale water.
Q: But mosquitoes could still breed in my water garden?
A: Yes. But using oxygenating plants and a circulating pump will reduce the risk considerably. For more details on that, read the water garden column archived at my web site. Go to
Q: I have a pond. Are there some fish that particularly like to feed on mosquito larvae?
A. There's an excellent article at landscaping.about.com by David Beaulieu that you should read. David says that minnows and goldfish are good larvae-munchers. But the Gambusia affinis is so effective that it has acquired the nick-name, "Mosquito Fish." With increased awareness of West Nile Virus, this once-obscure fish has suddenly become popular. You can find David's article at
addresses are quite complicated and hard to copy from the printed version. This is why any URL that I mention in these columns can be accessed directly from the online versions archived at my web site.)
Q: What about Citrosa plants, that ads guarantee to repel mosquitoes?
A. Not exactly true, I'd say. Just putting a pot of Citrosa on your patio will do virtually no good at all. Why? To be effective, you need to crush the leaves to release the citronellal oil and rub it on your skin. When you do that, the oil released has approximately 30 to 40 percent of the repellency of DEET, according to studies at the University of Guelph in Ontario. The point is that no plant can effectively repel mosquitoes until the oil is released.
Q: So, is there a plant that is more effective than Citrosa?
A: According to the same study, crushed lemon thyme (Thymus X citriodorus) has 62 percent of the repellency of DEET. Another benefit: lemon thyme is much cheaper. Lemon thyme has very aromatic evergreen foliage that forms a dense mat and displays tiny lavender flowers in summer, so it's attractive as well as practical. Let me know if you want information on where to buy it.
Q: Any risks to be aware of?
A: There's always the chance you might have an allergic reaction. Test a
small amount on your inner forearm a few times over a couple of days. If
there's no allergic reaction, you should be fine.
Q: Any other ideas?
A: Install a couple of bat houses! While you're asleep, the bats will be tirelessly scooping up literally thousands of skeeters that would otherwise be waiting to feast on you. Again, let me know if you need more info on bat houses.
But above all, control or eliminate the amount of standing water on your
landscape and you'll have a lot less scratching to do this summer!
The Plant Man is here to help. Send you questions about trees, shrubs and landscaping to snipped-for-privacy@landsteward.org and for resources and additional information, including archived Plant Man columns, visit