Common Name: Live Oak Gallfly

Scientific Name:  Callirhytis pomiformis

Kingdom:  Animilia
Phylum:  Arthropoda
Class:  Insecta
Order:  Hymenoptera
Family:  Cynipoidea
Genus:  Callirhytis
Species: C. pomiformis



Have you ever heard of a creepy insect that holds tons of baby flies until their adulthood?  This insect lives in trees and is commonly found in forests.  In the winter months, they are completely frozen and sealed from the outside elements.  In the spring, the insect opens and releases all the adult flies that have grown inside.  But, the really cool thing is that the insect is parasitic and eats some of the guests that have grown in it. 

The Live Oak Gallfly has many different shapes and sizes.  One of the biggest Gallflies found is three centimeters wide.  Most commonly they are green and spiky, but on rare occasions one might find a yellow or brown colored Gallfly.  Gallflies are implanted in the tree branch by wasps.  Once implanted, the Gallfly grows in order to produce a mass number of flies.  Once the flies are released, the Gallfly shell dies and falls to the forest floor.

The Live Oak Gallfly was first discovered in Great Britian.  However, they are now commonly found today in any forest.  Gallflies grow wherever the wasp implants them on the tree.  So, wherever there is a concentration of wasps, there is likely to be a concentration of Gallflies. 

The Live Oak Gallfly is attached and grows from to the tree.  The insect lives off of the nutrients and moisture in the tree itself.  Once the fly larva grow, the Gallfly eats some of the baby flies that are held inside of it.  As strange as it sounds, the most common predator of the Live Oak Gallfly is the wasp and the fly itself. 

Although finding all this information was challenging, it was worth it because I learned that a Live Oak Gallfly holds young maturing flies and eats off of some of its own baby flies.   I will certainly be on the lookout for a Live Oak Gallfly when I next visit a California forest.  Of course, where there is Gallflies, there will be wasps.  So, beware on your hike!

Author:  Nolan P.

Date Published:  3/2013

Allen, Katy Z. Life Science. United States of America:Holt Rinehart Winston, 2007.