WSU Extension

Hortsense

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



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Caption: California gallfly "oak apples"
Photo by: R.S. Byther
  
Common Insects, Mites & Vertebrates : California gallfly
(revision date: 4/30/2013)


Biology
The gall of this cynipid wasp larva is the largest and most conspicuous of the galls on oak. It is a twig gall that is often called 'oak apple'. It starts out green and gradually becomes red on the sunny side. Later in the season, the gall turns brown or grayish just before the adult wasps chew their way out. The gall does no apparent damage to the tree and is easily removed without harming the twig. The gall is generally round and sometimes kidney-shaped. During its development, the gall may host up to a dozen larvae.
Management Options

Non-Chemical Management
  • Hand remove where practical.
Select non-chemical management options as your first choice!

Chemical Management

None recommended.

Images

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Caption: California gallfly "oak apples"
Photo by: R.S. Byther