It’s almost a given that most things we grow have insect enemies. Often these don’t cause much damage at all, but others can not only deform our plants but even kill them. For some pests, insecticide treatment works well and for others, natural means are available.

Japanese Beetles

One of the more obvious insect pests, Japanese beetles, eat plant leaves and if left unchecked, can totally destroy any garden plants. This goes for shrubs, too. What to do?

If infestations are light, the beetles can be held at bay by hand-picking. I drink Folgers coffee and the empty containers serve as the destination for hand-picked Japanese beetles. The container has a removable cap, which should be set back on after dropping a beetle or beetles in it.

In order to kill the beetles, I fill the coffee container half-full with water and then spray Raid Home & Garden insect killer in the water. When beetles, or any pest, for that matter, are dropped in the mixture, they die almost immediately.

For very bad infestations, pesticide is one solution. Japanese beetle larvae live in the ground and can be controlled by drenching the soil with diazinon or Dylox. Few homeowners go that far, though, and instead mostly rely upon traps. Like everyone else, I prefer to do without pesticides if at all possible. Some natural controls do a good job of keeping the Japanese beetle population down, but they do not kill them all, just enough for us to harvest at least the bulk of our crops. These natural methods include Japanese beetle traps as well as milky-spore disease, Bacillus popilliae. Spread this on the lawn and within days, it will begin its work of killing beetle grubs.

One gardening friend raises raspberries and several years ago, Japanese beetles destroyed his plants. He tried hand-picking morning and night and that couldn’t begin to keep up with the infestation. And he was reluctant to use pesticides because berries were already set on. Japanese beetle traps helped, but the insects were so numerous that the traps needed emptying several times a day. The takeaway from this is that we must not allow Japanese beetle populations to reach such epic proportions.

Cucumber Beetles

As if it weren’t hard enough to get cucumber seeds to germinate during our cold, wet springs, our cukes have an insect enemy that seems omni-present, just waiting for the seedlings to emerge so they can begin chewing on the leaves. The pest is the cucumber beetle, or striped cucumber beetle.

These slim, yellow-and-black-striped beetles measure about 0.2 inches long. When disturbed, they fly off the plants.

The damage inflicted by cucumber beetles is considerable, since they not only chew holes in the leaves, skeletonizing them if allowed to persist, but also eat the stems. In addition, these creatures transmit viruses and harmful bacteria, so it makes sense to keep after them and don’t allow them to gain an advantage.

It is possible, at least early in the season, to simply hand-pick the beetles and squash them between the fingers. Later, when the pests become too numerous, hand-picking has little effect. When the infestation reaches that stage, rotenone-based insecticide can take care of the problem. I have had excellent results with Malathion, too. Rotenone, though, is made from a plant, while Malathion is a chemical treatment.


Tiny, 0.1-inch, wedge-shaped and often quite colorful insects jumping on your crops indicate a leafhopper infestation. Often, the damage from these pests isn’t noticeable, but that doesn’t mean they aren’t doing their dirty work.

Leafhoppers can cause leaf curl and discoloring. Some leafhoppers carry plant viruses, too. These pests ruin vegetable plants as well as asters, roses and rhododendrons, so if you have more leafhoppers present than seems normal, it may be time to apply either rotenone or Malathion.

Stalk Borers

These insect pests either enter the cornstalk at ground level and work their way upward or crawl up the stalk and work their way down. Either way, it’s bad news for corn plants. Infected plants usually become deformed and in the case of the sweet corn in my garden, topple over at a point where the borer has done the most damage.

Effective treatment via pesticides is lacking. Fortunately, for large corn patches, it’s mostly the rows nearest grassy areas that see the highest degree of infection. But for a home gardener with only a small patch, the entire crop can fail because of borer damage. There is a natural way to at least partially control these pests, and that will be dealt with toward the end of this column.

Ambershell Snails

What are those small, thin-shelled snails that get all over my vegetables and flowers? Well, they are a new menace and suddenly showed up seemingly from out of nowhere several years ago.

These creatures do physical harm to all plants. But the biggest threat is one seldom considered, that of inadvertently eating one of these tiny snails. While some ambershell snails are large enough to be easily seen, immature snails are tiny and it is quite possible for one or several to hide in your lettuce or other salad ingredients, unnoticed.

I know of no effective treatment for these pests, other than picking them off and dropping them into a container or crushing them between the fingers. But for the latter, make sure to wear gloves for your own protection. Diatomaceous earth spread around the periphery of your garden can help, but it doesn’t last long, only until the first rain or even a heavy dew, which causes the powder to cake and thus become ineffective.

The best thing we can do, other than hand-picking, is to carefully wash, rinse and closely scrutinize all salad ingredients before serving. Discard anything that has a tiny snail on it.

Natural Defenses

We gardeners have natural, non-toxic ways to thwart insect pests and the diseases they carry. Here are some ways to have a healthy garden.

First, always remember that a clean and neat garden is a healthy garden. That means keeping weeds down by weeding gardens regularly. This has other benefits, too. A carefully weeded garden has considerable visual appeal. Also, no matter what the crop, it will do better without the need to compete with weeds for soil-borne nutrients.

At season’s end, it is important to clean garden beds by disposing of all old plants. Don’t leave those bean vines or those tomato or cucumber vines in the garden because if they had even a trace of disease, they may transmit it to next year’s crop. Of course perennial favorites such as asparagus require different care. Once the fern-like asparagus stalks turn yellow and woody, it’s time to dispose of them. And then weed the asparagus bed with a vengeance and after that, apply a cover of compost. Garden outlets sell a number of different types of composts, from composted cow manure to seafood compost. It all works and your garden needs to have its nutrients replenished, since our crops and yes, even the weeds, use up nutrients.

Next, if certain crops had insect or disease problems this season, take care not to plant the same crop in the same place next year. Crop rotation is important for several reasons. Different crops have different needs and if planted on the same plot each season, certain nutrients will become reduced to a dangerously low level. Also, crop rotation helps prevent the spread of disease.

Weeds outside the garden can harbor insect pests that can easily enter the garden. So keep grass trimmed and make sure the edge of any garden is as far away from tall grass as possible. This helps keep insects away from and out of the garden.

Flower gardens, too, benefit from being weeded and cleaned. Once perennial plants have died back, remove all old stalks and stems. This goes a long way toward keeping your precious perennials healthy.

Finally, any containers or even trellises that hosted diseased plants must be thoroughly cleaned with a solution of bleach and water before re-use. Even garden tools that were used on infected plants can harbor harmful bacteria, so make sure to sterilize these, too. Even the soil from containers that held diseased plants should be discarded. It’s okay to compost such soil, since the heat from the composting process will kill soil-borne diseases.

So the long and short of having a healthy garden comes down to keeping a clean and tidy garden. And isn’t that what we all want anyway?

Tom’s Tips

Orange saves tools. How many times have you searched for a garden tool unsuccessfully? Tools, especially small ones such as trowels, have a habit of hiding in plain sight. But a bit of orange paint on the handle, or even some orange surveyor’s flagging wrapped around the tool will make it more difficult for the tool to remain hidden and easier for you to locate it.


Tom Seymour of Waldo is a homeowner, gardener, forager, naturalist, Registered Maine Guide, amateur astronomer, magazine and newspaper columnist and book author.