WSU Extension


Common Insects & Mites
Asian lady beetle 
Bark beetles 
Brown marmorated stink bug 
Brown soft scale 
California gallfly 
Conifer aphids 
Cottony camellia scale 
Cutworms and loopers 
Eriophyid mites 
Exotic longhorned beetles 
Fall webworm 
Lecanium scale 
Oystershell scale 
Pamphilid sawflies 
Pear slug 
Root weevils 
Sapsucker damage 
Shothole borer 
Sowbugs, pillbugs, and millipedes 
Spider mites 
Spotted wing Drosophila (SWD) 
Tent caterpillars 

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Caption: Aphid colony
Photo by: Unknown
Common Insects & Mites : Aphids
(revision date: 4/30/2013)

Many species of aphids attack ornamental plants. Some are fairly host-specific, while others may attack a dozen or more different host species. In some cases, aphids may only withdraw nutrients and moisture with their sucking mouthparts, causing no real damage when their populations are small. Others secrete "toxins" in their saliva while feeding, causing various deformations, even when their numbers are low. Feeding aphids excrete "honeydew," a sweet, sticky, shiny substance which accumulates on leaves or other surfaces. Honeydew serves as a nutritious food source for development of black sooty mold fungi and is attractive to honeydew-feeding insects such as ants. As aphids grow, they shed their "skins" or part of their exoskeleton like other insects. Cast skins serve as signs of current or past aphid presence. Many species of aphids prefer lush, tender new shoots and leaves, while others feed on the top or bottom surfaces of leaves, on stems, or on branches.
Management Options

Non-Chemical Management
  • Various predators, such as lacewing larvae, ladybird beetle adults and larvae, syrphid fly maggots, soldier beetles, and certain midges, help manage aphids. Some of these predators can be purchased by home gardeners.
  • Apply a fairly strong stream of water to the plant. Use care that the water stream does not damage flowers or young leaves.
  • Hand-wipe or prune to control small, localized infestations (when practical).
  • Control honeydew-feeding ants, which may protect aphid colonies from predators.
  • Provide proper nutrition. High levels of nitrogen encourage aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer.
Select non-chemical management options as your first choice!

Chemical Management

If nonchemical management options do not give satisfactory control, several insecticides are effective in managing aphids. However, the insecticide must be registered for the host plant. Find a list of registered pesticides for a specific host by referring to the fact sheet for aphids on that host.


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Caption: Aphid colony
Photo by: Unknown
Caption: Aphid cast skins
Photo by: R.S. Byther
Caption: Lily aphids
Photo by: R.S. Byther
Caption: Green peach aphid
Photo by: Unknown
Caption: Aphid colony
Photo by: R.S. Byther
Caption: Aphid colony
Photo by: R.S. Byther
Caption: Aphid colony
Photo by: A.L. Antonelli