What is this growing on this white oak?

Asked June 3, 2020, 12:51 PM EDT

Hello, I noticed this white, fussy looking, ball with brown tips, growing on a white oak in my yard. There are 2 of them. I poked it with a stick and it seem firm and difficult to open. I'm wondering if it is harmless or if I need to take action. Please help! I can send more pictures if needed. Thank you! Sidenote; a friend of mine also saw one in New York State. Take care, Agnes

Talbot County Maryland

7 Responses

This looks like a wool sower gall. These are caused by a tiny wasp (Callirhytis seminator), the wool sower wasp. http://bugguide.net/node/view/180960/bgimage

A gall is simply unusual tissue swelling. They are not concerning and the tree should be fine. Here is more on galls https://extension.umd.edu/hgic/topics/shade-tree-galls


Thank you!
Wondering, will it turn into the dark hard gall (found on many oaks) or will it disappear?

Take care,

This is not the kind of gall that hardens. It is soft and will naturally fall apart and disappear from view.


Thank you for your help!!!

Take care,

Ok I do have one more question.
A friend on mine has noticed them more that ever this year.
Why would that be?
Are conditions somehow super ideal this year?
Conditions like moisture and lack of disturbance?


There can be a number of reasons why insect populations boom and bust. They are indeed often tied to weather conditions as well as predator/parasite numbers, which can boom and bust for similar reasons. Perhaps the weather was conducive to their survival and the vulnerability of the oak tissue at just the right time, before most of their predators had emerged from winter dormancy.