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
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 6 weeks.
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
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
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.