Aphids

Aphids are as reliable as weeds. More than 4,000 species of aphids have been identified devouring nearly every plant in our garden.

These critters are often named for their favorite food, such as the bean aphid, wooly apple aphid and root aphids.

Physical Description:

There are black, brown, red, purple, pink, green and yellow aphids. Some have wings and others do not. They all have about 1/8�?(3 mm) soft bodies are pear shaped, with two long antennae and a soda-straw mouth part adapted for extracting plant juices. They also have whip-like antennae at the tip of the head, and a pair of tubes, called cornicles, jutting from the other end of the body. The cornicles fire a defensive spray when the aphid is threatened.

Range & Habitat:

Aphids can be found throughout North American orchards, gardens and meadows.

Life Cycle:

Aphid reproduction is geared to produce the most offspring in the least amount of time. Eggs overwinter on woody stems, hatching during spring into females, which feed en masse. After about a week or two they will then continuously give birth to live nymphs without having to mate. This all-girl system of reproduction without fertilization is called parthenogenesis.

As conditions become too crowded a winged generation is produced, which flies off to other plants and begin the process all over again. Eventually, overcrowding due to rampant reproduction and lower fall temperatures trigger a generation of true males and females. These mate during the fall, producing the all-female eggs which overwinter the population into the following spring.

Most species have many generations living no longer than one season. Some species feed on cereal crops or weeds for part of the year and on fruit trees other times.

Signs & Damage:

Aphids are typically drawn to yellow and pale green, weak plants often found on new shoots and underside of leaves. They are also known for transmitting viruses and other pathogens.

All have piercing, sucking insects usually found on new growth, undersides of leaves and stems leaving behind a sticky, wet substance called honeydew. This material promotes mold and attracts ants.

If allowed they will feed in numbers and will make entire stem or plant turn yellow with a sticky residue. Leaves will turn brown and fall off. Tomatoes will get Blossom End Rot; have dead spots on leaves, leaf roll and stunted growth. Fruit trees will have swollen twigs and branches covered with a white puff.

The ant-aphid relationship is similar to that of the farmer and his cows. In exchange for honeydew, Farmer Ant protects his herd of aphids from predators and even moves it to greener pastures when food supplies are depleted.

Garden Targets:

Most vegetables and ornamentals are susceptible. Cabbage aphids infest brassicas to the point where entire plants are not worth harvesting. It’s nearly impossible to dislodge the masses once they have accumulated inside the heads of brussel sprouts, broccoli or cauliflower.

Pea aphids mob peas and beans, while bean aphids swamp not only peas and beans but spinach, chard, beets and rhubarb as well. Apple, pear and other orchard trees can be damaged - even stunted �?by wooly apple and green peach aphids. Root aphids are taken by ants to feed on the roots of beans, carrots, corn, lettuce and parsley.

Cultural Controls:

Avoid planting species that attract aphids. These include birch trees, roses and some vegetables such as brussel sprouts. Consult your local garden centre for help choosing aphid-resistant plants. Also be sure the plants are healthy and have proper growing conditions. Weak or stressed plants are more susceptible to attack. Attract native predators and parasites by planting pollen and nectar plants;

Remove garden debris after harvest (especially cole crops) to kill eggs and cultivate the garden soil 6�?to 8�?where possible. Repeated tillage helps to discourage ants that nest underground, Rotate crops and don't overfeed, as too much nitrogen will encourage an aphid infestation. Be sure to keep grass mowed around your garden.

The reflection from aluminum foil mulch disorients flying aphids, keeping them from lighting on plants surrounded by it. The shiny surface also reflects light and heat back into the plants. Lay out strips of foil around the base of vulnerable plants and hold them in place with rocks or bricks. Keep a close watch to be sure that the increased temperature does not harm the plants, if plants wilt from heat radiated by the foil, remove it.

For small infestations, hands pick and destroy the aphids

Repellents:

Interplant your prized plants with Alliums (e.g. garlic and chives), anise, coriander, nasturtiums and petunias

Exclusion:

Row covers effectively protect vegetables and can be left on cole crops until harvest, temperatures permitting.

Traps:<

Using their attraction to yellow against aphids, sticky traps can be made of bright yellow tiles, boards, or banners coated with motor oil, petroleum jelly, or commercial traps such as Tanglefoot. Bright yellow plastic plates filled with a little soapy water will also drown any aphids that fly into them. These work best positioned at the base of target plants.

Plantings of sunflowers and milkweeds also make good trap crops

Bio-Control:

Encourage beneficial insects and birds to visit your garden. Also consider planting flowering groundcovers in home orchards to attract predators and parasites. 

Ladybugs and lacewings can be effective in controlling aphids and are available from many nurseries. Before introducing any predators, reduce aphid numbers by pinching off severely affected plant parts or hosing off most of the aphids.

Ladybugs/ladybeetles need to be encouraged to form (or be released) at the beginning of the season before the aphid population takes off.

For best results with ladybugs, choose the right time of year and time of day to release them. Ladybugs are most active when the weather is warm, from April to September. Dusk is the best time of the day to release them, Water the foliage where the aphids are feeding. The hungry and thirsty ladybugs will be attracted to the water-drenched foliage and find the aphids for food. They do have a tendency to disperse when released. Prior to releasing ladybugs spray with a mist of Seven-Up pop. This sticky substance will prevent the wings from being used to fly away. Both the ladybug adult and larvae are predators.

In greenhouses you can release aphid midges, spiders, assasin bugs, big-eye bugs, praying mantids and soldier bugs are also good predators.

Parasites such as the chalcid and braconid wasps and others can help reduce aphid populations once they become established. Look for “aphid mummies�?the hollow remains of aphids that have already been parasitized. Do not disturb. Friendly bugs have left their legacy within and when the eggs hatch, more parasites will emerge to claim more aphids. The orange wormlike larvae of the gall, or aphid midge, will also do in plenty of aphids. They are invaluable greenhouse allies that, unlike many other beneficials, will keep busy year round.

Remember to provide the basics: water, shelter and food. Plants may develop some damage but should outgrow it. If pesticides are applied when predator populations are present, they may be harmed and prevented from keeping aphids in check.

Sprays & Dusts:

For vegetable crops and small ornamentals, spray smaller plants frequently with a strong stream of wate. The aphids will fall off and not find their way back to the leaves.

Soap sprays are highly effective against aphids on garden vegetables. One study found a 97% reduction in aphid numbers just one day after application, and aphid predators and other beneficials were unaffected.

Dormant oil spray for fruit trees and roses will prevent larvae from emerging from eggs laid on bark or stems.

A dusting of diatomaceous earth will dry up aphids, but beneficial insects may also suffer.

Home Made Sprays:

Boiling rhubarb leaves distills oxalic acid, poisonous to man and aphids if consumed. Use 2 pounds of leaves per quart of liquid soap. Use elder leaves instead of rhubarb to spray rose shrubs. Teas made from garlic or green onions and strong limewater also work. Three parts 70% rubbing (isopropyl) alcohol to 4 parts with a tablespoon of liquid soap added makes a very effective desiccant, finally, plant juice made from infested leaves will wipe aphids out.

Many homemade sprays have been successful against aphids. Tea made from 1 part mint and 4 parts water, steeped and filtered, will deter them.

As a last resort spray nicotine spray which can be made from tobacco stems or soaked cigarette butts. Both are effective, but toxic to people and animals. Don’t plan to use it on roses, however, as it turns the flowers black. Also, tomatoes, peppers and potatoes are susceptible to tobacco mosaic virus, which tobacco preparations can spread.

(Yes folks, this is my article)