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AphidAphids on Roses

Aliases The Serial Sucker; Macrosiphum rosae

Hangout: Rose bushes; especially on stems, buds and young leaves
Physical Features: Pink or green; 1/16" long; soft-bodied

Life Cycle
Rose aphids prepare for next spring's assault by laying hundreds of eggs on rose canes. After the young aphids hatch, they spend their entire lives gorging on their victim's life juices and producing more criminals. Too many on one bush can force some aphids to move and begin attacking another rose bush. Unless winters are mild, adults will die and only the eggs will survive until the next spring.

So Long, Suckers!

1. Patrol the area

  • Pursue perpetrators in areas of new growth and the undersides of new leaves twice per week in spring and summer. Use a hand lens.
  • Look for areas sticky with honeydew or an unusual number of ants.
  • Check and see if any leaves are curled, disfigured, or sticky. Also look for sabotaged flowers that have an unhealthy appearance.
  • Recording what your investigations reveal will help you find and stifle future intrusions. Be sure to note the victimized areas and compare the number of intruders to the last time you policed the grounds.

2. Make a positive I.D.

  • There are almost as many kinds of aphids as there are kinds of plants-rose aphid is just one example. Do some research on other types of aphids if you don't think rose aphid is what's ailing you. The Internet and the Cooperative Extension office are great resources, with lots of mug shots of these bandits

3. Do a thorough background check

  • Not only should you learn about aphids, but you should also get to know the squadron of beneficial insects covering the area. Many hunt down aphids, restoring law and order. However, aphids aren't just sitting ducks-they have ants for bodyguards. Ants will tend aphids for their honeydew and protect them from aphid-eaters, so look for ways to deter ants, too.

4. Determine the danger level

  • Plants can fight back if the invasion isn't severe.
  • Letting these rascals raid your landscape just a little can be good because it provides a food source for lots of beneficial insects. Good guys will eat aphids as appetizers and then devour many more bugs for the main course.
  • Seedlings are much less able to cope with assaults than larger plants.
  • Unfortunately, honeydew is an ideal breeding ground for some molds.

5. Make a plan

  • Do-Nothing Method
    Healthy plants combat aphids using chemical warfare, even without your help. Plants give off volatile chemicals when attacked by aphids. To top it off, these same chemicals signal aphideating bugs that aphids are in the area.
  • Manipulative Measures
    -Bring out the S.W.A.T. team! Aphids' soft bodies make this the easiest S.W.A.T. session you'll ever have. Just squash them with your fingertips!
    -Spray aphids off plants with a forceful water jet from hoses. Aphids don't easily climb back onto plants, especially if it's a hot, sunny day.
    -For small, localized raids cut off leaves or branches and drop in soapy water.
    -Carefully look over new transplants for aphids. Keep them separated from your other plants until the invasion is gone.
    -Aphids prey on plants stressed out from over-fertilizing and incorrect watering, so do your best to boost your plants' health.
  • Secret Agents
    -Luckily, this determined and detrimental bunch has lots of natural predators. Lady beetles, lacewings, parasitic wasps and many others crack down on large aphid attacks.
    -Pesticides can be deadly to aphid predators, so avoid using them.
    -Plant nectar-producing flowers, like coriander and fennel, to attract these natural enemies.
  • Armed and Dangerous
    -Suffocate hatching aphids in early spring with dormant oil, purchased from a home and garden store. Follow the directions and don't use within 30 days of sulfur products to prevent scalding plant leaves.
    -If the invasion is intense, spray a solution of water and insecticidal soap, which isn't as toxic to beneficial insects as other insecticides. Do this early in the day so plants dry by nightfall. Check the label to be sure the product is registered for use on the plant you're spraying, and follow the directions for use, storage, and disposal.
    -Avoid pesticides that kill many kinds of insects because they knock off beneficial bugs that eat these suckers.

6. Evaluate the results

  • Aphids reproduce quickly, actually giving birth to females that are already pregnant, so keep good records of changes in population size and tactics you used to control them.

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For more information, contact Scarlet Tang or Todd Murray
WSU Cooperative Extension (360) 676-6736
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