Hidden Garden Party: Who’s Eating Whom?

aphids on cantelope leaf

Heavy aphid infestation on the underside of a cantaloupe leaf. Photo: Ashley Bodkins

Who loves a party? I know I do, especially a summer BBQ with all the family favorites! Insects are no exception and really know how to have some fun. Pictured above is a party of aphids, which are tiny little suckers — literally. They are soft bodied insects that suck plant sap with their piercing, sucking mouthparts.

aphid damage leaf curling

Twisted, deformed leaves are a symptom of aphid feeding damage. Photo: Ashley Bodkins

Aphids can come in many colors ranging from shades of green to black. They suck juice right from plant tissues, resulting in bent and twisted leaves as seen in the picture above. Aphids are generally only found on the underside of leaves and can be in very large numbers. Once a colony is established females can even reproduce without a male.

They secrete a sweet, sugary waste liquid that is called “honeydew”. Sometimes a fungus grows on the
honeydew, which is called sooty mold and looks like someone smeared coal soot on the plant.

Seeing ants on your plants can be your first sign that there is an aphid infestation. Ants love honeydew and often “farm” aphid colonies to reap the benefits.

ladybird beetle

The ladybird beetle is a natural enemy of aphids. Photo: Ashley Bodkins

Aphids can transmit plant virus diseases, but generally they aren’t found in large enough numbers to warrant a chemical control. Mother Nature actually Ahas some really interesting predators for aphids. In fact, the beautiful red with black spotted ladybird beetle (ladybug) is an avid aphid hunter and can eat more than 5,000 aphids throughout its four-part life cycle.

lady beetle larva eating an aphid

Ladybird beetle larva eating an aphid. Photo: Lenny Wells, University of Georgia, Bugwood.org

Other natural predators include lacewings, flower fly larvae, and parasitic wasps. Evidence of natural predators include “aphid mummies” which are light brown, hollow aphid bodies that were once inhabited by parasitic wasp larvae.

aphid mummies

Mummies of oleander aphids parasitized by Aphidius sp. wasp. Note the hole in the aphid at the top right of the photo indicating a wasp has emerged. Photo: David Cappaert, Bugwood.org

syrphid larva

Flower fly larva feeding on an oleander aphid. Photo: David Cappaert, Bugwood.org

Physical control of aphids can be accomplished by spraying the pests with a strong stream of water. This causes them to fall off the plant and hopefully disrupt their feeding. As a last resort, use chemical
controls such as insecticidal soap or Pyrethrum products.

By Ashley Bodkins, Senior Agent Associate and Master Gardener Coordinator, Garrett County, Maryland, edited by Christa Carignan, Coordinator, Home & Garden Information Center, University of Maryland Extension. See more posts by Ashley and Christa.

2 Comments on “Hidden Garden Party: Who’s Eating Whom?

  1. Is it really appropriate to label insecticidal soap as a chemical? I think of organic gardening as non-chemical.

    Like

    • Insecticidal soap is a registered pesticide. Yes, it is less toxic than some other options, but one should consult the product label for information on appropriate uses and precautions.

      Like

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