Here we list the primary garden “pests” that affect urban gardens of the Fox Valley, Wisconsin, and how to contend with them. We know that garden damage from pests can be discouraging, but these are easy enough to deal with, especially if you notice them early or, as in the case of rabbits, prevent them in the first place.
Rabbits
Rabbits will clearcut some crops and leave others alone. In our experience, rabbits love to eat: leafy salad greens like lettuce and spinach, kale, broccoli, legume seedlings such as beans and peas, peppers, eggplants, sunflowers, and strawberries. They don’t seem to eat garlic, onion, tomatoes, potatoes, squashes, asparagus. Shrubs like red and black currants, when young, need winter protection (fence or wrap with burlap) against rabbit damage. We are also told that rabbits in different neighborhoods have different tastes!
The least expensive way to keep rabbits away from the varieties that they like is 3-feet tall poultry wire. The fencing sold as “rabbit fencing” generally doesn’t work because the wholes are too big.
Cabbage Butterfly Larva
These are the white butterflies you see flitting around gardens all summer. They lay eggs on brassica plants (e.g., kale, cabbage, broccoli, Brussels sprouts), eggs hatch into green larva that eat holes in the leaves and leave feces behind. The more they eat, the larger they–and their droppings–become. If you don’t mind holes in the leaves, the larva themselves can be simply washed off of smooth leaves, but they are much harder to remove from broccoli heads and layers of a cabbage head. Bacillus thuringiensis (Bt) is a bacterium harmless to people (approved for organic agriculture) but deadly to the larva. It is available as a liquid concentrate and pre-mixed spray sold under a variety of brand names.
Cucumber Beetles
These small black and yellow beetles suck juices from leaves, stems and fruits on cucumbers, melons, and squashes. If plants are established and vigorous before the onset of the beetles, they can usually withstand them. However, young plants or those stressed by drought or flooding can be overcome and die. Both neem oil and diatomaceous earth are organic pest controls for cucumber beetles, but we have had better luck with diatomaceous earth as a control method. When there isn’t rain in the forecast, dust the affected plants with DE in a flour sifter or sieve (as you would powdered sugar on a cake!).
Squash Bug
Adults fly in, lay eggs on leaves and stems of squash plants. The eggs hatch into nymphs that grow quickly into squash bugs that destroy leaves, stems, and squash fruits. In early summer, watch the undersides of squash plant leaves for clusters of brownish-red eggs to appear and remove them by sticking masking tape to them and peeling away.
Squash Borer
These larva bore into the squash vines, causing them to wither and die. Watch for the brownish eggs to appear, singly, on leaves and stems and remove them with masking tape as for the squash bug eggs. If you notice a vine turning yellow and withering, inspect the stem for a bulging and discolored spot that may harbor a larva. If there is a lot more to the plant, you can cut this part off. You can also do surgery on the stem, cutting into it and carving out the larva. Another option is to try to suffocate the larva by covering the affected portion of the stem with soil.
Slugs
Slugs are not a problem every season, but if it has been wet and you notice large holes in seedlings or young plants (e.g., legumes, peppers), slugs may be the culprit. Inspect your plants early in the night, when the slugs come out to feed. Hand removal is effective. Take away all mulch for a short while to dry up the moist habitat they like, and try slug traps made by pouring (cheap) beer in saucers set around in the garden. An alternative to beer is a slurry made of yeast, sugar and water. It’s the yeast and sugars that apparently attract them to the liquid that they find inescapable.