The Plant Man column
for publication the week of 05/30/04 - 06/05/04
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
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 www.landsteward.org
then click on the column title under "The Plant Man" heading.
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
http://landscaping.about.com/cs/pestcontrol/ You can click on a direct
"hot link" from this column at my web site. (Some web 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
The Plant Man is here to help. Send you questions about trees, shrubs
and landscaping to firstname.lastname@example.org and for resources and
information, including archived Plant Man columns, visit
www.landsteward.org where you can also subscribe to Steve's free