Piercing/sucking feeders

Aphids (Rose aphid, Macrosiphum rosae;
Potato aphid, Macrosiphum euphorbiae)

Photo 11: Aphid.
Aphids are small, inconspicuous insects that feed in groups near the tips of new shoots and flower buds. Those found on roses are generally green or pinkish and up to 1/8 inch (3 mm) long.

Aphids feed by sucking plant juices, causing distortion of young leaves and stunting new growth. Flowers may also be affected when aphids feed on the buds. watch for honeydew, a clear, shiny, sticky waste product that collects on the leaves below the aphids and attracts ants. A black fungus called sooty mold also grows on the honeydew.

Ladybird beetle larva eating an aphid
Photo 12: Ladybird beetle
larva eating an aphid.
Look for beneficial insects where you see aphids. Lacewing and ladybird beetle larvae and adults are among the naturally occurring predators of aphids. Tiny parasitic wasps also control aphids by laying their eggs inside the aphids. The wasp larva feeds inside the aphid, killing it and leaving mummies-dark, swollen, motionless aphids with a hole in them.

Parasitic wasp emerged from mummified aphid
Photo 13: Parasitic wasp emerged
from mummified aphid.

While they have many natural predators and parasites, aphid populations can increase rapidly. Spraying with water can dislodge aphids. Do this early enough so that leaves dry by sunset. Biorational insecticides such as insecticidal soap are effective on aphids. Since insecticidal soaps work well on aphids and have low toxicity, they are suggested over conventional insecticides. Insecticidal soaps must contact the aphids directly. Conventional insecticides for aphids include pyrethrins, malathion, acephate (Orthene), and chlorpyrifos (Dursban). A long-term strategy is to add beneficial insects (such as ladybird beetles or lacewings) to the area, though it can be difficult to get good control of the aphids. Feeding ladybird beetles honey before release can improve their retention on the plant.

Twospotted spider mites (Tetranychus urticae)

Twospotted spider mites
Photo 14: Twospotted spider mites.
Mites are not insects, but are closely related to both insects and spiders. They are a yellowish green with a black spot on each side of the body. Mites are very small and difficult to see. A magnifying glass may aid in viewing mites

Mites feed by sucking plant juices out of individual cells from a wide variety of ornamental plants including roses. This causes small yellowish stippling (like spray paint droplets) on the foliage of host plants. Also look for very fine webbing on leaves and stems. As a result of heavy mite populations, leaves may turn yellow and drop from the plant. You can also check for mites by shaking branches over a white sheet of paper. The mites show up as tiny moving specks.

Twospotted spider mite damage. Notice bleaching of color in leaf.
Photo 15: Twospotted spider mite damage.
Notice bleaching of color in leaf.
Insecticidal soap and horticultural oil are biorationals for mites, although subsequent application is necessary. If the population is high, conventional pesticide use may be warranted. Mites are not insects. Consequently, pesticides called miticides are used for control. Dicofol (Kelthane) is an available miticide. Conventional insecticides with miticidal properties are appropriate. Read the product label to see if spider mites are listed. Focus mite control on the undersides of leaves and treat the entire plant.

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