Four Bad Bugs...
Stop Them Organically
Many of the moths and and butterflies you see flitting about in your garden may be lovely to look at, but they also deposit eggs which turn into leaf - eating worms which could destroy those plants you have so carefully nurtured.
Three insects that are prevalent with the warm fall season are aphids, cabbage loopers, and tomato horn worms. Aphids suck nutrients from plant leaves, fruits, and stems, causing the foliage to curl, pucker, and turn yellow. This may cause vegetables to be stunted or misshapen. Aphids like the undersides of new leaves, buds and tender stems. They are less than 1/10 inch long, and can be green, brown, black or pink. When first noticed, use a heavy stream of water to spray the offenders off of the plant. It may be necessary to do this several times. If the infestation is heavy, use an allium spray which will be mentioned later in this article. Occasionally, aphids will choose a single plant to infest in your garden. You may want to leave this plant to the aphids as a host plant. They may stay away from your other plants if given one succulent specimen to victimize. Aluminum foil, white plastic or straw placed at the base of plants can confuse the aphids flying overhead so they can't tell where to land. Floating covers seem to be effective for keeping aphids from plants. Interplanting chives, garlic, onions and petunias with vegetables and roses may also discourage aphids. Lacewings and lady bugs feast on aphids so you may want to include plants which attract these beauties among your vegetables. Examples include scented geraniums, dill, and cilantro. Allow the dill and cilantro to form flower heads which will attract lacewings in great quantities. Toads and many birds are also aphid eaters.
Cabbage loopers can cause tremendous damage to plants such as cabbage, lima and snap beans, broccoli, brussels sprouts, cauliflower, Chinese cabbage, collards, kale, lettuce, parsley, radishes and turnips. Interestingly, red cabbage has been found to be less attractive to these invaders. The looper is a light green caterpillar with yellowish stripes running down its back. The cabbage looper's parent is a brownish night - flying moth with a silver spot in the middle of each forewing. Eggs are greenish white, round, and laid singly on leaves. Look for small to large ragged holes in leaves. Plant celery and amaranth as host plants which will attract cabbage loopers. Intercrop with marigolds, alliums, rosemary, sage, tansy, and thyme which may deter these worms. Since the pupae will survive during the winter months be sure to clean up garden debris at the end of each gardening cycle. Tunnels made from fine screening or row covers can prevent the moths from flying in to lay eggs. Many birds and toads like to eat cabbage loopers. Rotate crops every 3-5 years with plants which are not attractive to cabbage loopers. Lacewings, lady bugs, and trichogramma wasps feast on loopers.
A related pest is the cabbage maggot-a small white legless worm with a blunt end, about 1/4 to _ inch long. The parent resembles a house fly and lays eggs in the soil at the base of the plant. The cabbage maggot overwinters as a pupa in garden soil. It tunnels into plant roots and stems, which causes wilting. All plants in the cabbage family can be infected, as well as collards, peas, radishes and turnips. The seedlings of all these plants are the most vulnerable. Add juvenile stage parasitic nematodes to your soil to attack cabbage maggots before planting. After planting row covers or collars around the stems of young plants are good protectors. Radishes and turnips can be used as bait crops to attract cabbage maggots. When they become infested, pull up and destroy the plants. Plant very early on in the fall to avoid the maggot. Sparrows, wrens and toads are more effective than insect predators for ridding your garden of cabbage maggots. Robber flies and spiders can help control the flies which lay cabbage maggot eggs.
The imported cabbage worm is a light green caterpillar with one yellow stripe. The adult is a white, day-flying butterfly. Inter-planting has little effect on this pest. But cornmeal placed around cabbage family plants attracts the worms. After ingesting the cornmeal, the worm becomes bloated and dies. There are a few birds which will eat these worms. Row covers are a good barrier which can prevent the butterfly from laying eggs.
Does the sight of a green horn worm cause you to scream? This 3-5 inch caterpillar has white stripes and a horn on its rear end. Chewed leaves and fruit, along with black or green droppings, will alert you to its presence. A large, mottled, gray or brown moth with five orange spots along each side of the body is the parent. These moths fly quickly and hover like hummingbirds. The 2 inch long pupae have a curved handle and overwinter 3-4 inches underground. Tomatoes, peppers, dill, potatoes, and eggplants all attract this pest. Bt, allium spray, and hand-picking are all effective controls. Many songbirds and toads relish eating horn worms. If a horn worm has a papery cocoon on its back, natural parasites have already laid their eggs inside. Allow the worm to live somewhere out of the garden so the parasites can reproduce. Braconid and trichogramma wasps and praying mantids are also predators. When you notice these beautiful moths in your garden, be aware that one of these pests may be lurking on your plants in a few weeks.
Leaf eating pests can be controlled in an existing garden by spraying plant leaves with a simple, foul tasting (at least to the worms) spray. Add about _ cup of crushed garlic and onion to one pint water, let set overnight. Add some powered coffee or tea, then strain. Add this mixture to a quart of water with a pinch of cayenne pepper and 4 or 5 drops of vegetable oil. Spray on the afflicted plant. This spray is not harmful to humans, but will discourage pests. Most insects will avoid foods treated with caffeine. Bacillus Thuringiensis (Bt), a naturally occurring bacteria which will kill insect larvae, can be bought as a powder to mix with water, or as a spray. However, there are many types of Bt so you must read the labels carefully to be sure you are purchasing the type which will destroy your specific type of larvae. Dipel, Safer, Biotrol and Thuricide are some trade names. To be effective, Bt must be eaten by the larvae.
There are also many animal friends who can help control the damage done by garden pests by eating their larvae. Among these are bats, birds, toads, lizards and snakes. Before tilling a new bed leave the ground fallow for a few weeks, so that skunks and moles can dig up harmful grubs and larvae. Place toad houses in several places in your gardens and build bat houses to hang from trees to attract bats. For instructions on building toad and bat houses consult books about organic gardening or find related articles in issues of Organic Gardening.
By Lois Lockhart and Mary Sisson Eibs
Email the authors at gardengoddess2@msn.com and momherb02@yahoo.com
TOG is a 501(c)3 non-profit organization and can be reached by phone at (520) 670-9158, or by email (tucsonorganicgardeners@hotmail.com). Our mailing address is: P.O. Box 27763, Tucson, AZ 85726.
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