Place the lady beetles at the base of infested plants or in the crotches of low branches. Lady beetles will crawl higher into the plant in search of aphids. University of California research indicates that high numbers of lady beetles are required to control aphids. One large, heavily infested rose bush required two applications, spaced a week apart, of about 1, lady beetles each. Aphids are very susceptible to fungal diseases when it is humid. These pathogens can kill entire colonies of aphids when conditions are right.
Look for dead aphids that have turned reddish or brown; they'll have a fuzzy, shriveled texture unlike the shiny, bloated, tan-colored mummies that form when aphids are parasitized. Weather can also impact aphids. Summer heat in the Central Valley and desert areas reduces the populations of many species, and aphid activity is also limited during the coldest part of the year. However, some aphids may be active year-round, especially in the milder, central coastal areas of California.
In some situations ants tend aphids and feed on the honeydew aphids excrete. At the same time, ants protect the aphids from natural enemies. If you see ants crawling up aphid-infested trees or woody plants, put a band of sticky material e.
Don't apply sticky material directly to the bark of young or thin-barked trees or to trees that have been severely pruned, as the material may have phytotoxic effects. Wrap the trunk with fabric tree wrap or duct tape and apply sticky material to the wrap. Alternatively, ant stakes or containerized baits may be used on the ground to control ants without affecting aphids or their natural enemies.
Prune out other ant routes such as branches touching buildings, the ground, or other trees. Before planting vegetables, check surrounding areas for sources of aphids and remove these sources. Some aphids build up on weeds such as sowthistle and mustards , moving onto related crop seedlings after they emerge. On the other hand, these aphid-infested weeds can sometimes provide an early source of aphid natural enemies. Always check transplants for aphids and remove them before planting.
Where aphid populations are localized on a few curled leaves or new shoots, the best control may be to prune out these areas and dispose of them. In large trees, some aphids thrive in the dense inner canopy; pruning out these areas can make the habitat less suitable. High levels of nitrogen fertilizer favor aphid reproduction, so never use more nitrogen than necessary. Instead, use a less soluble form of nitrogen and apply it in small portions throughout the season rather than all at once.
Slow-release fertilizers such as organic fertilizers or urea-based time-release formulations are best. Because many vegetables are susceptible to serious aphid damage primarily during the seedling stage, reduce losses by growing seedlings under protective covers in the garden, in a greenhouse, or inside and then transplanting them when the seedlings are older and more tolerant of aphid feeding.
Protective covers will also prevent transmission of aphid-borne viruses. Silver-colored reflective mulches have been successfully used to reduce transmission of aphid-borne viruses in summer squash, melon, and other susceptible vegetables. These mulches repel invading aphid populations, reducing their numbers on seedlings and small plants. Another benefit is that yields of vegetables grown on reflective mulches are usually increased by the greater amount of solar energy reflecting onto leaves.
To put a reflective mulch in your garden, remove all weeds and cover beds with mulch. Bury the edges with soil to hold them down. After the mulch is in place, cut or burn 3- to 4-inch diameter holes and plant several seeds or a single transplant in each one. In addition to repelling aphids, leafhoppers, and some other insects, the mulch will enhance crop growth and control weeds. When summertime temperatures get high, however, remove mulches to prevent overheating plants. Ready-to-use reflective mulch products include silver-colored plastic sold in rolls.
You can also make your own by spray-painting construction paper, landscape fabric, or clear plastic. If you use plastic mulches, you will need to use drip irrigation underneath.
Landscape fabric and most paper mulches will allow water to flow through. Another way to reduce aphid populations on sturdy plants is to knock off the insects with a strong spray of water. Most dislodged aphids won't be able to return to the plant, and their honeydew will be washed off as well. Using water sprays early in the day allows plants to dry off rapidly in the sun and be less susceptible to fungal diseases.
When considering whether to apply insecticides for aphid control, remember that most larger plants can tolerate light to moderate levels of aphids with little damage. Larger aphid populations often rapidly decline due to biological control or when hot temperatures arrive. Often a forceful spray of water or water-soap solution, even on large street trees, when applied with appropriate equipment, will provide sufficient control.
If insecticides are needed, insecticidal soaps and oils are the best choices for most situations. Oils may include petroleum-based horticultural oils or plant-derived oils such as neem or canola oil. These products kill primarily by smothering the aphid, so thorough coverage of infested foliage is required.
Soaps, neem oil, and horticultural oil kill only aphids present on the day they are sprayed, so applications may need to be repeated.
Although these materials can kill some natural enemies that are present on the plant and hit by the spray, they leave no toxic residue so they don't kill natural enemies that migrate in after the spray. These and other insecticides with contact-only activity are generally ineffective in preventing damage from aphids such as the leaf curl plum aphid or the woolly ash aphid, which are protected by galls or distorted foliage. These materials may be phytotoxic to some plants, so check labels and test the materials on a portion of the foliage several days before applying a full treatment.
Supreme- or superior-type oils will kill overwintering eggs of aphids on fruit trees if applied as a delayed-dormant application just as eggs are beginning to hatch in early spring. On plums dormant applications right after leaves have fallen in early November are preferred. Aphids are the tiny green insects that you might not even notice are crawling in your garden until you look closely.
These fascinating bugs can number in the thousands, but what exactly are they doing all over your plants? Aphids eat the sap by sucking it from plant leaves, stems and roots. This is why they congregate so densely on trees, flowers and other plants.
Some aphid species are attracted to specific plants. Aphids are particularly drawn to young plants and budding flowers. Plant sap is mostly sugar and water and is low in protein, so aphids have to consume a large amount of it to meet their protein requirements. You might find honeydew on the leaves of your garden plants if enough aphids are present.
The honeydew residue is not inherently damaging but it can cause problems for some infested plants. Sooty mold, a fungus, thrives on sugary substances, so it can grow quickly on the honeydew and cover leaves and branches.
Predatory insects found in gardens can keep aphid numbers in check Aphid predators include ladybirds, parasitoid wasps, lacewing larvae, predatory bugs and hoverfly larvae Biological controls for aphids on greenhouse plants can be purchased. Jump to What are the main aphid predators? Biological control. What are the main aphid predators? Ladybirds There are more than 50 species of ladybird in the UK.
Hoverfly larvae Hoverfly larvae are legless maggots with flattened, relatively broad bodies up to 12mm long. Lacewing larvae Lacewing larvae eat aphids and other small insects, which they seize with their curved jaws.
Predatory midge larvae Predatory midge larvae, Aphidoletes aphidimyza , are yellowish orange maggots up to 3mm long when fully grown. Parasitic Parasitoid wasps various species These insects are more accurately termed parasitoids as they kill the host, something parasites do not usually do. Earwigs Earwigs are omnivorous, feeding on small invertebrates and plant material. Predatory beetles Some ground and rove beetles climb plants to feed on aphids, the rove beetle Atheta coriaria is available from some biological control suppliers for control of aphids and some other glasshouse pests.
Birds Birds including blue tits will feed on aphids. There is some evidence that gardens where birds are encouraged aphid numbers are lower. Aphid parasitioid wasp Aphelinus sp. Biological control Some aphid predators, including predatory midges, parasitic wasps, lacewing larvae, rove beetles, hoverfly larvae and ladybirds, can be bought by mail order or some garden centres as biological controls.
See also Protect your garden. You may also like. Conifer aphids. Currant aphids. Currant blister aphid. Cypress aphid. Fruit aphids. Green spruce aphid. Ground beetles and rove beetles. Harlequin ladybird.
Hellebore aphid. Large willow bark aphid. Mealy cabbage aphid. Pear-bedstraw aphid. Privet aphid. Raspberry and blackberry aphids. Rose root aphids. Rosy apple aphid.
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