365 Urban Species. #261: Oak Apple Gall Wasp

[urbpan]

Urban species #261: Oak apple gall wasp Amphibolips confluenta

Acorns aren't the only round objects falling from oak trees this time of year. Spheres, about the size of golf balls or slightly smaller, green and mottled with red, mysteriously appear on the sidewalk. Later, many more will be found--larger, light brown like dead leaves, sometimes entire, more often with a single hole in the thin crust. These mysterious objects are not pods from outer space, or oak tumors; they are galls: the protective nurseries for young insects, usually given the quaint name "oak apples." The mother insect enlists the help of oak trees, symbolic of strength and live itself, to shelter her growing offspring. Known, somewhat anticlimactically, as the oak gall wasp, the tiny non-stinging insect deposits her egg in the flesh of an oak leaf. Along with the egg is a hormone that induces the oak tree to form a gall around the wasp egg. The larva develops within a shield of plant material, a capsule suspended in the center of the orb.

At least 200 species of organisms use oak trees to form galls of one kind or another. Other plants that often play host to gall wasps and gall mites and other creatures include goldenrods, maples, and roses. Galls cause very little damage to the host plant, and gall wasps are not considered to be serious pests.

The gall is not an impregnable fortress, and many predators recognize wasp galls as sources of food. Birds, notably woodpeckers and chickadees, poke holes in galls when they encounter them aloft. Fallen galls are fair game for squirrels and other mammals, and enterprising predatory wasps may gnaw their way into galls in trees and on the ground. If the gall wasp larva escapes all these predators and survives to adulthood, it chews its way out, leaving a small neat hole in the papery gall, which falls with the leaves of autumn.


Sliced open to see the larva inside.

Comments

[ms-cantrell.livejournal.com]

that is so cool. i had no idea insects could do stuff like that.

[pinkveneer.livejournal.com]

so there's just one little guy in those pods?

[okaree.livejournal.com]

They look almost tasty when sliced open like that... :E

[http://users.livejournal.com/purplebunnie_/]

My mom used to tell me that if you took a rusty nail and swirled it around in the old, dry-er ones, you could make a cheap type of ink.

This was before I understood quill pens.

[rinkori.livejournal.com]

That is amazing. I had no idea.

[brush-rat.livejournal.com]

Thanks bro, I never quite understood those things. I'd heard they were some kind of seed pod and I'd heard they were somehow related to insects. In a weird way I guess both of those are right. Nature is really weird.

[http://users.livejournal.com/_bazilisk_/]

Galls have large amounts of untapped poetic metaphoric potential. They symbolize:

-The incredibly interconnected genius of nature (duh)
-Parasitism
AND
-Nurture, caring

all at the same time...

I sense a poem brewing...

only problem with these sciencey poems I make is no poetry fans understand science well enough. Darn.

But think about it! It's beautiful and ugly at the same time- esp. that cross section, it's striking as all hell, almost astronomical-looking, a shining sun with rays of structure spreading out to the edge of the sphere it's contained in...a shining sun with a MAGGOT at the epicenter...(but maggots are cute babies XD )

Wow. I am having a serious 'wowed by the world' moment here.

[momomom.livejournal.com]

That is the perfect structure for the classic high school physics class egg drop project.

[ndozo.livejournal.com]

It's hard and fun (for me anyway) to try imagine the evolutionary path that finally settled in to this relationship

[miz-geek.livejournal.com]

I always wondered what the heck those things are!

The words "gall wasps" always reminds me of Kinsey - his first subject before humans.

[drocera.livejournal.com]

Well that was quite interesting! I learned something new today!

[burning-brain.livejournal.com]

That is totally freaky fascinating.

answered my question

[(Anonymous)]

Thanks for this neat information. We had found a few on the ground under an oak tree and wondered what they were. You answered our question!!

lolz

[(Anonymous)]

this is cool

[ndozo.livejournal.com]

The ink thing is real. From Wikipedia: Iron gall ink (also known as iron gall nut ink or oak gall ink) is a purple-black ink made from iron salts and tannin from vegetable sources. It was the standard writing and drawing ink in Europe, from about the 12th century to the 19th century, and remained in use well into the 20th century...