Are you looking for natural garden pest control options? Like many home gardeners, I started growing my own fruits and vegetables in part to avoid the toxic chemicals used on most commercial produce. After all, why put in all that time and effort to eat poison? It didn't make sense to me.
Just walking down the chemical isle in the hardware store, i.e., the “garden helper area” or whatever they call it, gives me a headache. When I first started out, I tried some of the fancy “organic” pest control options, but I've found that simple home remedies work pretty well. My most used options to get rid of unwelcome garden guests are hand picking; coffee grounds; traps and physical barriers; and encouraging beneficial insects and animals.
Hand Picking Bugs
I know it sounds gross, but hand picking bugs works fairly well for several species that show up in my garden. I use it for Colorado potato beetles, squash bugs, cucumber beetles and cabbage worms.
Potato beetles and cabbage worms can be picked any time of day, as they are slow moving. Squash bugs and cucumber beetles are best nabbed in early morning, before they have a chance to heat up and speed up.
To “hand pick” bugs I usually prep a large yogurt container or something similar with a couple inches of water in the bottom mixed with some soap to break the surface tension. Knock or drop the bugs in, and they don't come out. I don't recommend squashing mature potato beetles with your bare fingers, as they will bite and their shells are quite hard.
Here's an immature potato beetle.
Here's a mature potato beetle.
If you can catch these early before they become widespread, hand picking is easy. I have also used diatomaceous earth for potato beetles (and cabbage worms), but hand picking is my preferred tactic. Make sure to check on the underside of leaves for clusters of bright orange eggs, and smash them or scrape them into your soapy water. The boys make some extra cash in the summer by acting as “bounty hunters” and earning a set amount per bug collected. You can also buy insect soap specifically designed to be sprayed directly on bugs.
Cucumbers beetles can be terrible, plus they spread bacterial wilt, which gets in the soil and can cause problems for years after the initial infestation. First off, work to maximize your soil fertility – better soil = plants that are less likely to attract pests and are more resistant when they attack.
At our old place, where we had poor, heavy clay soil, once the cucumber beetles showed up, and the bacterial wilt spread, I was not able to grow vine crops well again. Here, the cucumber beetles show up, but they don’t do much damage. I’ve got a mixed clay/sand/loam and much more organic matter.
To control cucumber beetles, it’s best to get them early in the morning, when they are cooler and less active. They like to gather in blossoms, so I will gently shake a blossom into my container of soapy water, or use something like a popsicle stick to scoop them into the water. Sunflowers are great for attracting cucumber beetles – they love them! They gather on the sunflower heads and I shake them/brush them from the head into the soapy water. You can eliminate large qualities of them very quickly. The sunflower trap works almost any time of day.
Cabbage worms, like most insect pests, will show up in much greater numbers when your plants are stressed in any way. When I've accidentally planted them too close together so they are overcrowded, or dealt with drought or poor soil, my cabbage worm problems have been much worse. Make sure cabbage family plants have ample room to grow (plant 2-3 feet on center) and give them plenty of nitrogen in the form of compost or rotten manure. It's hard to have soil that's too rich for these plants. When your soil is good and your plants are healthy, damage will be minimal and plants will recover easily. You can also fertilize with fish emulsion, weed tea or compost tea to give plants an extra boost of nutrition.
See Working with Nature – Shifting Paradigms and Building Soils Naturally: Innovative Methods for Organic Gardeners for more information on building a healthy garden ecosystem.
If cabbage worms have gotten out of control, DE (diatomaceous earth) and Bt (bacillus thuringiensis) are two products available at garden centers that will slow them down. DE is made of finely ground rock containing the fossilized shells of diatoms. The grains are very sharp, and injure soft bodied critters. (Don't breath this. I'm sure it's not great for toads and frogs, either.) Bt is a form of naturally occurring bacteria that effects the larva stage of insects, basically causing their stomachs to explode. Because of it's overuse in genetically modified crops (the Bt gene is spliced into a crop such as corn so the entire plant becomes a pesticide – read more at Would You Feed Your Kids Pesticide Chips?), many insects are becoming resistant to these bacteria (there are multiple strains of Bt). As you can see, each product has some problems, which gets me back to hand-picking and encouraging healthy plants.
To help clean cabbage worms off of harvested broccoli or cauliflower, cut the head into florets for maximum surface area (to expose hiding spots) and soak the florets in hot, salty water for 10-15 minutes. The cabbage worms should float to the surface of the water. Rinse under fast running cold water to dislodge any stragglers. If you're still concerned, cook by blanching in boiling water for 3 minutes, and a couple more may float out. Otherwise cook/use as normal. The worms are completely edible, just not common table fare for most of us.
Squash bugs are fast moving and breed very rapidly. The adults resemble stink bugs, some of which are actually beneficial, so when they first showed up in my garden, I didn't realize they were trouble. I soon learned the error of my ways. Squash bugs can suck and chew a plant to death in days. Look for egg clusters on the underside of leaves and smash them or scrape them into your soapy water.
The nymphs can be treated the same way. Neem oil is supposed to be effective on the nymphs if they are hit directly, but it didn't slow the ones in my garden down very well.
By the way, the mature squash bugs smell like fruit loops when you smash them. I tried to get a picture, but they weren't cooperating. The young ones don't smell as strong, and they don't taste like much of anything, just “green”. (Yes, I ate some bugs last summer. I was curious, and figured it was time for payback.)
Update: Reformation Acres has a nifty post about using duct tape to catch nymphs and round up eggs. Check it out here. Also, I've recently started researching entomophagy (eating bugs) in more detail, and found out that squash bugs and many other common garden pest are edible. If you're curious, you can read Eating Bugs – Free Food from Your Backyard.
Coffee Grounds for Flea Beetles
If you end up with leaves that look like they've been sprayed with buckshot, and all you see are tiny, fast moving black bugs about the size of fleas, chances are that you have flea beetles.
In my garden, they like to go after early spring growth. Beans and peppers are often hit particularly hard, brassicas get some damage but not as much. Coffee grounds can be applied after damage is spotted to give the plants a chance to recover (I've brought nearly dead plants back from the brink), but I've taken to applying the grounds when the plants are small to avoid damage in the first place. Around mid-winter I start saving up and ask friends to start saving their grounds as well.