When it comes to nature, we have to take the weird with the wonderful. The California oak gall wasps (Andricus quercuscalifornicus) are no exception.

Ever wonder what those apple-like orbs on oak trees are? Contrary to popular belief, these red balls are not fruits - but galls. What the heck is gall, you might ask? Great question. Galls are actually the product of larvae being injected into the tree’s branches by a particular species of wasp. Yep, weird right? Gall wasps have a parasitic relationship with oak trees by utilizing the trees defensive mechanism as a little wasp nursery. The wasp lays its eggs inside the branch or leaf, meanwhile introducing chemicals to the tree that forces its growth hormones to overproduce - creating a gall. This gall provides safety, protection from predators, and nutrients to the wasp larvae. Once the larvae are ready to “hatch” from the gall, they drill tiny holes and free themselves from their temporary home. Although this is considered parasitic behavior on’s part, the oak trees are typically unharmed. Keep your eyes peeled for these colorful galls next time you take a hike!

Check out this education video about gall wasps and oak trees narrated by David Attenborough.