Q&A

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,
Barbara Pierce
Tennessee

DEAR BARBARA:

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 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 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.

NF

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