Aphids in home yards and gardens (2024)

The life cycle of aphids is complex and varies per species. The cabbage aphid is a good example of a typical life cycle.

Female aphids do not need a male to reproduce. For most of the summer, wingless females give birth to live young instead of laying eggs. Cabbage aphids can complete up to 15 generations per plant season because they mature quickly and can reproduce throughout their lives.

In response to displacement by other aphids or declining host plant quality, winged (migratory) forms are produced that move to new plant hosts. They are poor fliers, but due to their small size they can travel for miles with the wind.

In the fall, male nymphs are produced that mature and mate with females.

• Dog killer eggs that survive the winter on the plant.
• In the spring, the eggs hatch and new female aphids give birth and reproduce.

Green peach aphidsfeeds on hundreds of different plants, including potato, pepper, cabbage, spinach, asparagus, aster, dahlia, iris and verbena. They are commonly found on cabbage, but do not cause serious damage.

They are yellow-green and have long cornices. The eggs can survive the winter.

Kalbladlusfeeds only on cruciferous plants such as cabbage and mustard. They are green with a waxy coating that gives them a gray-white appearance. They have short corollas and live in large clusters on the underside of the leaves, in the center of the cabbage head or on the youngest leaves.

Adults are present in both wingless and winged forms. You will likely see wingless females producing live young (nymphs).

Potato aphidcommonly attacks potatoes, tomatoes and other nightshade crops such as peppers, eggplant and morning glories.

Melon aphidfeeds on a variety of plants, especially cucurbits such as watermelons and cucumbers, but also asparagus, peppers, eggplant, asters, hollyhocks and lilies.

Brown ragweed aphidare common onRudbeckia, Cape flower and sunflower.

Oleanderbladluisfeeds on milkweed throughout spring and summer, but causes no damage to the plants.

They are 1/8 inch long, pear-shaped and bright yellow with black legs, long antennae and two black tail tubes at the end of the abdomen.

Landscaping plant aphids feed only on a particular tree or shrub and do not attack any other type of plant. For example, aphids attacking a quaking aspen would not attack an oak.

The most common aphids in the Minnesota landscape are onroses, spirea, poplar (aspen and white poplar), willows, oaks, maples, white pines, limes and fruit trees (especially apples and crabapples).

Aphids use thin, needle-like mouthparts to feed on plant sap. They congregate where they can feed on new, succulent growth on unopened flower buds, the undersides of young leaves and developing stems, twigs, bark and roots.

In many cases there are no visible symptoms of aphid feeding. Symptoms of severe aphid feeding include:

• Twisted and curled leaves
• Yellowed leaf
• Stunted or dead shoots
• Poor plant growth

When aphids feed, they inject saliva into their host plant to help digest the sap. After feeding, they excrete a sticky, shiny waste product called honeydew.

• Honeydew is a sugar-rich material that attracts ants, yellow jackets (especially in late summer and fall) and other insects that feed on it.

• It can coat bark, leaves and objects under the plant, including car windows and patio furniture, creating a sticky mess.

Honeydew generally does not cause damage, but it can cause leaves to stick together and can promote the growth of sooty mold.

• Red eighty mouldis a fungus that grows on honeydew and often occurs on trees with aphids.

• The fungus is not harmful to the tree, but can cause dark, cloudy spots on leaves and branches.

How to remove honeydew

It is not necessary to remove honeydew from plants as this will not harm the plants.

If honeydew is a major problem, treatment should be applied after the leaves begin to form (or when honeydew is noticed) to kill the aphids and reduce honeydew problems.

Dishwashing detergents and tar removers can be used to remove honeydew from structures and vehicles.

• You should scrub with a washcloth or sponge.

• Tar removers and harsh cleaners can damage painted surfaces and remove the clear coat from cars.

• Test it on a small area of ​​the surface to make sure it won't cause further damage.

Aphids can carry several plant viruses, including the cucumber mosaic virus. This virus can infect many vegetables, including squash, cucumber, pumpkin, melon, beans, spinach, tomato, lettuce and beetroot, as well as annuals and perennials such as impatiens, gladiolus, petunias, phlox and rudbeckia.

• Viruses can cause leaves to become spotted, turn yellow or curl.

• Plant growth may be stunted.

• In some cases the fruit may be deformed.

You can physically repel plants with a strong jet of water from a garden hose. This also helps to wash away any honeydew or sooty mold that may be present.

Aphids are not strong insects, and even a heavy rain shower can repel them. You may notice more aphids in seasons with lighter rain.

There are many natural enemies of aphids that are commonly found in gardens, includingladybugs,netwings, syrphid fly larvae and parasitic wasps. Because aphids can reproduce very quickly, it will likely take some time for the predatory insects to catch up and reduce the number of aphids.

Protect natural enemies by avoiding pesticides or using low-risk products. Encourage natural enemies by planting flowering plants that bloom at different times of the growing season.

In most cases, aphids cause little or no damage to plants and can be ignored. If aphids are causing problems and need to be treated, consider using insecticides.

Low risk pesticides

Several insecticides pose low risk to humans, beneficial insecticides and the environment.

Neem (azadirachtin) is a plant-based pesticide that discourages aphid feeding. It doesn't kill insects quickly, but it causes them to stop eating and die slowly.

Insecticidal soap, horticultural oil and pyrethrins can be effective in controlling aphids.

• Don't forget to spray the underside of the leaves as well as the top.
• These materials only kill aphids they come into contact with. Repeated applications may be necessary.

Pesticide residues

These products are effective for a week or more. Although they last longer, they also kill a variety of insects, including natural enemies. This can make aphid problems worse. Do not spray flowering trees or shrubs.

Common examples of pesticides available to consumers include acephate, permethrin, bifenthrin, lambda-cyhalothrin, cyfluthrin, and malathion.

Systemic pesticides

Systemic products, such as imidacloprid and dinotefuran, are applied to the base of the tree and transported through the sap to the leaves, stems and branches where the aphids feed. When the aphids ingest the pesticide, they die.

This process can take two to four weeks, depending on the product used and the size of the tree. Most of these products will also kill other insects that feed on leaves in trees. The use of systemic insecticides prevents pesticide drift, especially when treating large trees.

Systemic pesticides do not come into direct contact with natural enemies. However, imidacloprid and dinotefuran are highly toxic to pollinators. Avoid using these insecticides on bee-attractive plants or wait until the plants have finished blooming before treating them.

Professional services

You can also hire a professional landscaping company to treat aphids on trees and shrubs. They have the training and experience to successfully tackle an aphid problem. To seeThis is how you hire a tree care professional.

WARNING:Read all pesticide label directions very carefully before purchase and again before use to ensure proper application. Make sure the label states that it can be used for the specific plant you want to treat. The label is the final authority on how you can legally use pesticides.

When using pesticides, including low-potency natural or organic pesticides, follow all label directions and use standard pesticide safety practices for transporting, storing, mixing, applying and disposing of pesticides to protect yourself, your neighbors and the environment. to protect.

Woolly aphids usually alternate between two different host plants (some feed on only one host plant).

• They lay eggs on the primary host plant.
• The eggs survive the winter and female aphids hatch from the eggs in the spring.
• On the same plant, the females begin to produce live offspring without mating.
  • The aphids are clones of the female aphids that laid the eggs.

After one to two generations on the primary host, the new aphids will develop wings as adults. Winged female aphids fly to a secondary host plant and begin feeding and reproducing.

• Woolly aphids spend most of the growing season on their secondary host.
• Each female produces hundreds of offspring over several generations.
• The average lifespan of an aphid is about one month.
• They reach sexual maturity in four to ten days and can then produce their own offspring.

In late summer or early fall, a second generation of winged females is produced on the secondary hosts. The females then fly back to the primary host.

• Here the winged aphids produce males and females.
• These aphids mate and the females lay eggs.
• The eggs of this generation survive the winter and start the cycle again in the spring.

Woolly aphids feed on plant sap with their needle-like mouthparts. They can feed on leaves, buds, twigs, bark and even roots.

Symptoms of diet:

• Twisted and curled leaves
• Yellowed leaf
• Poor plant growth
• Low plant capacity

Also look for accumulations of waxy material and waste skins on leaves, twigs and bark.

Woolly aphids produce large amounts of honeydew (see Damage caused by aphids in the main section), which covers leaves, branches and anything under attack.

Fortunately, aphid damage usually only affects the appearance of a plant. It rarely affects plant health.

Many species of woolly aphids are found on deciduous trees and shrubs in Minnesota.

Woolly elm fluff

(Eriosoma americanum)

• Attacks American elm in spring, resulting in curled leaves with white cottony mass inside.
• These aphids move to blueberry bushes in early summer.
• In early autumn they fly back to the elm to overwinter.
• They do not cause major damage to mature trees and shrubs.
• They can be harmful if found in large numbers on blueberry bushes younger than three years old.

Mealy or aphids or maple aphids

(Prociphilus tesselterer)

• Forms dense, white, woolly clumps on silver maple leaves and twigs in early spring and on alder boughs and branches in summer.
• When maple leaves are severely affected, the leaves fold lengthwise, covering the aphids inside.
• The white, waxy threads do not cause any damage, but can be mistaken for a fungus.
• In the fall, the aphids produce males and females that mate and lay eggs on the maple trees.
• These eggs, and in some cases nymphs (young aphids), can survive the winter on branches of the alder.

Leaf curl aphid

(Prociphilus ashinifolius)

• Eat in spring with protruding ash leaves, causing them to become distorted.
• Feeding lasts until mid-summer.
• Winged forms then move to ash roots, where they remain for the rest of the year.
• Leaf curl aphids cause little or no damage to the ash.

In most cases, management is not necessary for the health of trees and shrubs, especially large mature plants.

As with other aphids, natural enemies (lacewings, ladybirds, hoverflies and parasitic wasps) ensure that the numbers of woolly aphids remain low.

Woolly aphids are not affected by horticultural oils and soaps, like other aphids. This is because the waxy secretions of the woolly aphids and the deformed leaves prevent the pesticide from penetrating the leaves.

Contact pesticides, such as permethrin, also do not work against woolly aphids for the same reason.

In cases where management is necessary to protect plants, systemic pesticides such as imidacloprid and dinotefuran are most effective against woolly aphids. However, imidacloprid and dinotefuran are highly toxic to pollinators. Avoid using these insecticides on bee-attractive plants or wait until the plants have finished blooming before treating them.

Consider hiring a professional landscaping company to treat your trees or shrubs.