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Organic pest control: what works, what doesn't: our nationwide reader survey reveals the best methods for managing common garden pests.

Last fall, MOTHER EARTH NEWS launched our Organic Pest Control Survey to learn more about what works and what doesn't when it comes to limiting insect damage in organic vegetable gardens. About 1,300 gardeners from across North America responded, providing new, region-specific insight into organic pest control.

Our survey had strengths and weaknesses. It included opportunities for open comments, which became the source for the practical tips in this article. But, although we asked many questions about specific methods, we failed to always list chickens and ducks, which we learned many gardeners regard as essential players in controlling Japanese beetles and other garden pests.

We were surprised by some of the results. For example, we suspected gardeners would report that coping with various root maggots was a challenge, but 90 percent of respondents reported getting good control with crop rotation. Similarly, flea beetles didn't make the list of worst pests because most gardeners achieve good control by using row covers and growing susceptible greens in fall rather than spring.

Ultimately, the survey revealed 12 widespread garden pests that give gardeners grief. Here are the nitty-gritty details, including down-in-the-dirt advice on how to manage each pest, plus details on which pests are the worst in each region.

1 Slugs took top honors as the most bothersome pest in home gardens, with 55 percent of respondents saying the slimy critters give them trouble year after year. Handpicking was highly rated as a control measure (87 percent success rate), followed by iron phosphate baits (86 percent) and diatomaceous earth (84 percent). Opinion was divided on eggshell barriers (crushed eggshells sprinkled around plants), with a 33 percent failure rate among gardeners who had tried that slug control method. An easy home remedy that received widespread support was beer traps (80 percent success rate).


Relying on bigger predators--such as chickens, garter snakes and ducks--appears to be the most dependable way to achieve long-term control of garden slugs, as well as several types of beeries, cutworms and many other pests. Ducks are reportedly sharp slug-spotters, whether you let them work over the garden in spring and fall, or enlist a pair to serve as your personal pest control assistants throughout the season.

"Hungry ducks follow me around the garden daily. They love slugs and turn them into eggs," commented a Mid-Atlantic gardener with 10 to 20 years of experience. In the Pacific Northwest, several longtime veterans of slug wars said ducks are a gardener's best (and most entertaining) way to end chronic problems with slugs.


2 Squash bugs had sabotaged summer and winter squash for 51 percent of respondents, and even ducks couldn't solve a serious squash bug problem. Most gardeners reported using handpicking as their primary defense, along with cleaning up infested plants at season's end to interrupt the squash bug life cycle. The value of companion planting for squash bug management was a point of disagreement for respondents, with 21 percent saying it's the best control method and 34 percent saying it doesn't help. Of the gardeners who had tried it, 79 percent said spraying neem on egg clusters and juvenile squash bugs is helpful. About 74 percent of row cover users found them useful in managing squash bugs.

Several respondents pointed out that delaying squash planting until early summer and growing the young plants under row covers results in far fewer problems with this pest. This makes sense because natural enemies of squash bugs become more numerous and active as summer progresses. Until then, keep scraping off those egg clusters, and handpick as best you can. Three readers shared this tip: In the cool of the morning, place open pizza boxes be neath squash plants. Jostle the plants and let the adult and juvenile squash bugs fall into the boxes, and then slide your captives from the boxes into a pail of soapy water. A creative idea from Editor-in-Chief Cheryl Long is to create a simple Squash Bug Squisher out of two thick boards and a hinge. For more details on how to build the squisher, and to read comments from fellow readers who are battling squash bugs, go to www.

3 Aphids were on the watch list of 50 percent of respondents, but the success rates of various control techniques were quite high. Active interventions, including pruning off the affected plant parts and applying insecticidal soap, were reported effective, but so were more passive methods, such as attracting beneficial insects by planting flowers and herbs. Several readers noted the ability of sweet alyssum and other flowers to attract hoverflies, which eat aphids. "We attract a lot of beneficials by planting carefree flowers in the vegetable garden, including calendula, borage, zinnias, cosmos and nasturtiums" (Midwest, more than 20 years of experience). Other respondents commented on the importance of having some aphids around to serve as food for ladybeetles, hoverflies and other well-known beneficial insects.


4 Imported cabbageworms came in fourth, with a 47 percent 'disapproval rating. If you see these little white butterflies in your garden, action to protect your brassicas before the cabbageworm moths lay eggs. Two widely accepted biological pesticides, Bt (Bacillus thuringiensis) and spinosad, received remarkably high effectiveness ratings: 95 percent for Bt and 79 percent for spinosad. Row covers had a reported success rate of 82 percent, while companion planting and garlic-pepper spray had disappointing failure rates in excess of 30 percent.


Several respondents said they rely on paper wasps to control cabbageworms. "They're friendly, docile and voracious eaters of cabbageworms. My garden is full of cabbage butterflies, but I've yet to see a single worm; the wasps beat me to it" (Mid-Atlantic, six to 10 years of experience). To attract paper wasps, place bottomless birdhouses in the garden to provide nesting sites. Gardeners in the South, Mid-Atlantic and Midwest noted that cabbageworm populations drop if yellow-jacket nests are nearby, which enhances the success of fall cabbage-family crops.


5 Squash vine borers had caused problems for 47 percent of the survey respondents. The best reported control methods were crop rotation and growing resistant varieties of Cucurbita moschata, which includes butternut squash and a few varieties of pumpkin. The C moschata varieties are borer-resistant because they have solid stems. Interestingly; if you're attempting to fend off squash vine borers, lanky, long-vined, open-pollinated varieties of summer squash (zucchini and yellow crookneck, for example) may fare better than hybrids, because OP varieties are more likely to develop supplemental roots where the vines touch the ground. Many gardeners dump soil over these places, so if squash vine borers attack a plant's main stem, the plant can keep on growing from its backup root system. Because borers attack stems, compact hybrids, which tend to grow from one or two main stems, are naturally more susceptible.

One tactic is to wait out the borer's egg-laying season. "To avoid squash bugs and squash vine borers, planting vining crops late and covering them with row covers until the first fe male flowers has been effective for us" (Midwest, six to 10 years of experience).

6 Japanese beetles slid in at No. 6, which is surprising because they don't pose problems in extremely hot or cold climates. Forty-six percent of respondents reported working in the unwelcome company of Japanese beetles, with handpicking being the most popular control method. Some gardeners grow trap crops of raspberries or other fruits to keep Japanese beetles away from plants. Several commonly used interventions--garlic-pepper spray, milky spore disease, pheromone traps and row covers--had high failure rates.


Numerous respondents said chickens ended their problems with Japanese beetles, with guinea fowl and ducks also recommended for ridding areas of Japanese beetle grubs and adults. Even if you don't let your chickens scratch in your garden, your handpicking may be more enjoyable because you'll have something tasty for your birds when you're finished collecting the beetles. In late spring, when Japanese beetle larvae are dose to the soil surface, letting wild, bug-eating birds work over the area can have a lasting impact, too. Several readers shared that having nesting pairs of robins and bluebirds (which feed insects to their young) is the best way to keep Japanese beetles from getting out of hand.


7 Tomato hornworms claimed the No. 7 spot, and were of concern to 42 percent of our survey respondents. Bt and handpicking were the preferred control methods, and several folks commented that tomato hornworms are among the easiest garden pests to handpick (probably because they're large, easy to spot and produce a telltale, pebbly trail). Many gardeners reported seeing tomato hornworms often covered with rice-like cocoons of parasitic braconid wasps. "I had a lot of tomato hornworms this year, but the wasps took them out! Just like in the photos online and in bug books!" (Mid-Atlantic, more than 20 years of experience). Gardeners named zinnias and borage as good companion plants for reducing hornworm problems.


8 Cutworms were a concern for 41 percent of respondents, and effectiveness ratings for using rigid collars (made from plastic drinking cups or cardboard tissue rolls) to protect young seedlings from damage were amazingly high (93 percent effectiveness rating). A common practice to reduce cutworm damage is to cultivate the soil's surface once or twice before planting and hope robins and other bug-eating birds will swoop in to gather the juicy cutworms. Big, sturdy seedlings are naturally resistant to cutworms, so many gardeners said they set out seedlings a bit late to avoid cutworm damage.

9 Grasshoppers were a problem for 40 percent of respondents, and they seemed to be getting worse. We received many reports that increases in rainfall seemed to trigger an explosion in grasshopper populations. Chickens and guineas reportedly give good control by gobbling grasshoppers, but keep an eye on your poultry helpers to make sure they don't harm crops. Gardeners described two interesting setups incorporating chickens for managing hoppers: a fenced garden with a fenced chicken "moat" around its perimeter, and a series of three small fenced gardens, each with a gate into the chicken yard for easy rotation of pecking services. (For instructions on building a chicken moat, go to If grasshoppers are getting worse at your place, you may need chickens more than you think.


10 Cucumber beetles wouldn't be so bad if they didn't transmit deadly bacterial wilt to cucumbers and melons, but as it is, 39 percent of our respondents named them as serious garden pests.


Neem, handpicking and good garden cleanup (removing all Plant debris) were all rated as effective control measures, and once again poultry received many honorable mentions. Row covers earned more widespread use for the control of cucumber beetles than for any other pest, with more than 80 percent of people who had tried row covers reporting them to be effective.

Seventy percent of gardeners who'd tried companion planting said this method works for controlling cuke beetles, and 64 percent of people who'd tried yellow sticky traps reported these work.

11 Corn earworms were pegged as serious pests by 37 percent of respondents many of whom get easy relief by using instruments ranging from oil cans to eyedroppers to add a few drops of canola or olive oil into the tips of ears, right when the silks start to show. Others reported using a standard solution of Bt in the same way, and several experienced gardeners pointed out the value of choosing varieties that have tight ear tips.


The corn earworm comments included several mentions of the ease with which earworm damage disappears if you pop off the end of the ear, thus making this pest not such a big deal. Raccoons, on the other hand, were reported to be a big deal, which was the main reason many gardeners gave for not growing corn. "If I plant sweet corn, the raccoons always eat it unless I fence them out" (Midwest, 25 years of experience).

12 Whitefly problems may be on the rise, because whitefly-plagued gardeners (36 percent reported a problem) often used exclamation points to emphasize their frustration with these tiny sucking pests. Insecticidal soap earned a high effectiveness rating (90 percent), though many respondents said they use Dawn or other dishwashing: liquids rather than regulation insecticidal soap. (Caution: Some research has found that repeated use of soap or detergent sprays can reduce yields.)


Garden Pest Control Trends

Pest Control on the Wing

"Wild birds are a huge help, and gardeners should be encouraged to provide both nesting habitat and feeding stations for them. The bluebirds, flycatchers and other birds that live on my property spend a lot of time around my gardens catching bugs, The much-despised house sparrow is also a terrific boon to gardens, so urban gardeners would be well advised to put out feeders even if that's the only bird they will attract" (Maritime Canada, six to 10 years of experience).


Are Six-Legged Changes Afoot?

One of the questions we asked in our survey was this: During the past three seasons, have there been noticeable changes in the insect activity in your garden? Thirteen percent of gardeners reported they'd had many more pest problems, and 29 percent reported slightly more problems. Several respondents noted that increases in rainfall during the past few seasons seemed to be associated with more grasshoppers. Also, the appearance of a new, exotic insect, the marmorated stink bug, has brought new pest control challenges to gardeners in Pennsylvania and nearby states (see Page 99 for more on these stinkers).

The Value of Beneficials

Seventy percent of survey respondents said they work to provide habitat for beneficial insects. Here's what they said about whether this effort had helped to reduce pest problems:
Seems like it has helped a great deal     32 percent
Seems it has been somewhat helpful        49 percent
Seems to have helped with some pests       6 percent
Doesn't seem to make any difference       13 percent

Broad-Stroke Pest Control

Along with working to improve your soil and thus grow healthier, more pest-resistant plants, several other common-sense approaches echoed through the comments sections of our survey. "The best way to beat the bugs is to plant more than you can use yourself. You can always give the surplus away" (North Central/Rockies, six to 10 years of experience). Others pointed out the advantage of setting the stage for beneficial insects and then simply standing back. From the Midwest: "I am willing to overlook some bug damage in order to provide good habitat for the beneficials reproducing all though the gardening season." From the South: "A balance of insects is the goal, and 'good' and 'bad' insects both have to eat."
Worst Garden Pests by Region

Ever wondered which pests thrive in your region and how your
region compares with others in North America? Here's the
breakdown. A high score (scale is 0 to 100) indicates the insect
was reported to always or often pose problems, while a lower
score indicates rare problems with that pest. Pests are listed
from most to least troublesome, and highlighted squares indicate
the worst two pests for the region.

                         Central    Gulf     New       Mid-
                         Midwest   Coast   England   Atlantic

Slug                        52       58       65        63
Squash bug                  58       54       51        54
Aphid                       46       61       47        49
Cabbageworm                 49       39       57        50
Squash vine borer           58       63       47        52
Japanese beetle             57       31       57        62
Tomato hornworm             50       67       44        43
Cutworm                     43       55       48        41
Grasshopper                 50       56       39        42
Cucumber beetle             49       42       51        49
Corn earworm                43       42       40        42
Whitefly                    36       57       34        36
Snail                       34       57       43        44
Flea beetle                 35       25       24        36
Colorado potato beetle      37       19       44        36
Leafhopper                  33       38       31        28
Mexican bean beetle         22       19       24        25
Cabbage root maggot         22       19       27        21
Harlequin bug               18       22       15        22
Armyworm                    21       28       11        16
Blister beetle              19       18       13        12
Onion root maggot           19       19       16        19
Carrot rust fly             16       15       17        17
Asparagus beetle            20       12       20        16

                         Central/    Pacific    Southern
                          Rockies   Northwest   Interior   Southwest

Slug                        52          80         50          45
Squash bug                  40          25         64          46
Aphid                       58          66         59          60
Cabbageworm                 53          37         50          29
Squash vine borer           27          19         61          28
Japanese beetle             24          21         52          22
Tomato hornworm             33          22         58          52
Cutworm                     50          40         53          41
Grasshopper                 65          35         58          51
Cucumber beetle             29          20         46          30
Corn earworm                42          19         47          33
Whitefly                    39          40         46          49
Snail                       32          60         45          48
Flea beetle                 26          22         37          23
Colorado potato beetle      42          15         34          23
Leafhopper                  28          23         41          33
Mexican bean beetle         15           9         29          13
Cabbage root maggot         27          24         22          14
Harlequin bug               19          12         27          16
Armyworm                    18           7         24          11
Blister beetle              16           7         21          13
Onion root maggot           17          12         15          10
Carrot rust fly             16          20         12          10
Asparagus beetle            14           8         15          11

Top-Rated Natural Methods for
Controlling Common Garden Pests

Pest                     The Three Top Controls

Aphid                    Insecticidal soap, attracting beneficials,
                         horticultural oil

Armyworm                 Bt (Bacillus thuringiens), handpicking, row

Asparagus beetle         Poultry predation, neem, handpicking

Blister beetle           Poultry predation, neem, handpicking

Cabbage root maggot      Crop rotation, beneficial nematodes,
                         diatomaceous earth

Cabbageworm              Bt, handpicking, row covers

Carrot rust fly          Crop rotation, beneficial nematodes,
                         diatomaceous earth

Colorado potato beetle   Poultry predation, neem, handpicking

Corn earworm             Bt, horticultural oil, beneficial nematodes

Cucumber beetle          Poultry predation, neem, handpicking

Cutworm                  Rigid collars, Bt, diatomaceous earth

Flea beetle              Insecticidal soap, garlic-pepper spray, row

Harlequin bug            Handpicking, good garden sanitation, neem

Japanese beetle          Handpicking, row covers, milky spore disease

Mexican bean beetle      Poultry predation, neem, handpicking

Onion root maggot        Crop rotation, beneficial nematodes,
                         diatomaceous earth

Slugs                    Handpicking, iron phosphate slug bait,
                         diatomaceous earth

Snails                   Handpicking, iron phosphate slug bait,
                         diatomaceous earth

Squash bug               Handpicking, good garden sanitation, neem

Squash vine borer        Growing resistant varieties, crop rotation,
                         beneficial nematodes

Stink bug                Handpicking, good garden sanitation, neem

Tarnished plant bug      Handpicking, good garden sanitation, neem

Tomato hornworm          Bt, handpicking, row covers

Whitefly                 Insecticidal soap, attracting beneficials,
                         horticultural oil
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Author:Pleasant, Barbara
Publication:Mother Earth News
Geographic Code:1USA
Date:Jun 1, 2011
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