DEAR NEW FARM:
My dilemma is with harlequin bugs. I have bought several
shipments of beneficial nematodes and applied them in October
2004, and again in June and July, and I have the worst infestation
of harlequin bugs ever (I have since had my money refunded
by the beneficial nematode vendor). Anyway, how can I get
rid of these before fall (as in right now)?! My cantaloupes
are being slaughtered by these things! By the way, I have
used: weed control (ruining my hands and back via the good
old labor method of pulling); I've sprayed Pyola, rotenone
w/pyrethin, and Bulls-Eye (a Gardens Alive product); I've
tried strengthening the plants by feeding with kelp/fish emulsion;
and I have put down newspapers and covered this lightly with
cypress mulch. Nothing seems to bother these things, and I've
never been so worried! Please help. As you can tell, I'm organic.
(Would using Sevin dust not be a good idea for organic growers?)
Thank you in advance,
We posed your question to Dave Wilson, a research agronomist
here at The Rodale Institute®. Dave answered a similar
question recently for New Farm reader Fred Johnson, who wanted
to know about OMRI-approved organic controls for harlequin
bugs. Please review that
answer here. Dave also had some specific advice for your
situation. Here’s what he had to say:
1.) Native parasitic wasps and tachinid flies attack harlequin
bugs or stink bugs, although the problem with these natural
parasites is keeping the population of the beneficials in
the area where you have the problem of the pests. This is
more easily accomplished in a greenhouse setting than it
is outside. As stated in my answer to Mr. Johnson, these
parasites are attracted to small-flowered plants, but the
grower needs to establish these plants early in the season
so they will act as an attractant to the beneficials. This
is before they would even see stink bugs in the garden and
so also well before they have any idea of whether or not
a population of stink bugs will be a problem that year.
It’s all about preventative maintenance.
2.) The weed-control issue is primarily about removing
an "overwintering" site for the bugs; controlling
weeds and removing crop residues reduces the overwintering
sites for the bugs. This can help control the population
next year and some of the population this year. Stink bugs
tend to become pests as nearby weedy areas dry out during
the summer, which then drives them from their "weed
refuge" into the garden.
3.) Each female can lay up to 30 clusters of 300 to 500
eggs. The eggs are characteristically placed in two rows.
In the cool temperatures, the eggs will hatch in about three
weeks. As the temperatures rise, the eggs will hatch in
less than a week. The nymphs develop into adults in 5 to
For small gardens, hand squishing of adults and eggs is
time consuming and back aching but still has the most impact;
it kills adults before they produce more eggs and/or kills
the masses of eggs while they are grouped together on the
underside of leaves.
4.) Spraying insecticidal soap can be effective to control
the nymphs but it must be thorough and repeated every three
to five days.
Once the bugs are seen, the strategy should be to squish
adults, squish egg masses and then spray insecticidal soaps
to control nymph, then finally spray the neem, pyrethrum
or sabadilla if needed.
It should be noted that pyrethrum—although approved
for organic production—is broad spectrum and is toxic
to bees. Typically, it breaks down rapidly in the soil due
to sunlight and moisture. When pyrethrum is used, there
is a rapid knockdown of the insects (but they may recover).
Finally, to answer Barbara's question about the product
Sevin (Carbaryl), this is
not approved for organic production.
Carbaryl is moderately to very toxic, and is labeled with
a “WARNING” signal word. It can produce adverse
effects in humans by skin contact, inhalation or ingestion.
Carbaryl is a wide-spectrum carbamate insecticide. Carbaryl
works whether it is ingested into the stomach of the pest
or absorbed through direct contact. The ecological problem
with Carbaryl is that it is lethal to many nontarget insects.
The pesticide is more active in insects than in mammals.
The destruction of honeybee populations in sprayed areas
is sometimes a problem. Carbaryl is moderately toxic to
aquatic organisms, such as rainbow and lake trout, bluegill,
and cutthroat. It is also moderately toxic to wild bird
species, with some low toxicity to Canada geese. Accumulation
of carbaryl can occur in catfish, crawfish, and snails,
as well as in algae and duckweed. Studies show residue levels
in fish 140 times greater than the concentration of carbaryl
in the surrounding water.
us with comments, suggestions and questions.