Thousands of caterpillers eating oak trees!

What type of caterpiller eats oak tree leaves? We have thousands of them in all of our oaks. They are defoliating the tops of the trees and working their way down. It literally sounds like it's raining when standing near these trees from all the droppings. Well, it is raining - caterpiller poop. They are large caterpillers, in all our trees (we live in a wooded area that is primarily hardwoods) and they are consuming amazing amounts.

I can't get a photo because the caterpillers are too high up in the trees to get to them. It takes binoculars to see them. I don't have any hopes of stopping them since they are so high up and there are literally thousands of them, but I would like to know what they are and what they will hatch into.

Gypsy moths here do that. I lost some fine oak trees. After all the leaves are eaten for a couple years in a row the trees die. I had to sweep the dropping off the deck and sometimes remove worms from my hair. It was terrible. I hope that is not what you have.

You may very well have forest tent caterpillars. These were a bit of a scourge around Louisville for several years recently. Their numbers tend to ebb and flow with environmental conditions and predator/parasite populations.

These are more fondly known as Malacosma disstria. Take a google at this species, and see if you can't find some of the caterpillars dropped to the ground to compare with photos.

Our tent worms here only eat the wild cherry trees. They are already done this year and flying away. I agree, you need to find what you have. There are ways to protect the trees in your yard, but you need to find out what you have.

IDing pests from high trees isn't the easiest thing, and certainly is no fun as you see foliage disappearing before your eyes.

cpartschick describes eastern tent caterpillar (Malacosma americanum) which prefers trees in the Rosaceae family, and really wears out Prunus serotina (wild cherry, black cherry) every spring. These caterpillars have obvious large tent-like nests. The forest tent caterpillar does not create the tents, tending to congregate on a silky mat along the trunk or main branches when not actively feeding.

This behavior made the forest tent caterpillar easy to deal with in the situations we found in Louisville on new nursery stock waiting to be planted, or young trees in the landscape. One had only to check in morning or evening for the large masses of caterpillars all in one wad/lump on the trunk, and then send them to their maker. Eastern tent caterpillars in their silky tents are harder to eliminate.

To carry this further...eastern tent caterpillar is the insect implicated in the amazingly destructive Mare Reproductive Loss Syndrome that struck the equine Thoroughbred industry particularly hard back in 2001. Thousands of foals and fetuses were lost due to this malady, and it severely changed the course of this industry in KY. The components of the Bluegrass landscape were permanently altered, too, as cherry tree after cherry tree was eliminated from the farms where these horses are raised.

Good information.
As much as I hate pesticides, the yearly spraying here has controled our gypsy moth in this area. I have never seen destruction and filth like this worm makes ever before.
The tent worms are nasty too, but are confined to their nests in early morning and are easily taken care of with a blow torch. Of course as with every emplosion of a species, their cycle comes when they are brought back into ck. (I hope)

Maybe I can find a branch low enough to capture a caterpillar for identification. I haven't seen any nests so far. It's just unreal how many trees are affected and how much these creatures eat and poop. I suspect the answer will be some type of moth as we have many different kinds.

Viburnum, that's very interesting and sad about the equine industry being affected. How do the caterpillars cause this? I'm totally ignorant about horse breeding.

This biological and economic disaster is still not totally explained. You can bet a tremendous amount of resources have been thrown at it to try to determine the precise cause. I don't own horses, but worked in the thoroughbred industry for a long time (my wife still does) and this turned things on their heads for some time.

I'm certainly not a veterinarian or a scientist, but I think the research has led to the belief that something in the caterpillar was an abortifacient in mares. It caused the loss of foals about to be born that year, and wreaked havoc in mares being bred for the following foaling season. A google search for MRLS (mare reproductive loss syndrome) will turn up a lot of information. The Gluck Center at the University of KY has done much of the research.

The numbers of caterpillars were so incredibly high, that they were crawling across fields and pastures in search of new plants upon which to feed. This is where it is believed that horses consumed the caterpillars while grazing on field grasses. What a freakish year.

I have photos somewhere (I think slides, not digital) of railroad tracks covered with eastern tent caterpillars roaming in search of food.

Thanks for the education. That's heartbreaking. Yes, I can imagine the impact on the industry.

Decided to go on a caterpillar safari. Ick! It was not fun getting 'rained' on. It looks like we may have two different types of caterpillars, but the vast majority are the multi-striped ones with black horns. It's hard to see them in the photo.

An example of the poop....

and the defoliation of the trees...

The one on the right looks like a Green-Striped Mapleworm.

http://images.google.com/imgres?imgurl=http://www.forestryimages.org/images/web/1669033.jpg&imgrefurl=http://www.bugwood.org/gfcbook/di.html&h=225&w=150&sz=32&hl=en&start=27&tbnid=_seogBe4ueD7HM:&tbnh=108&tbnw=72&prev=/images%3Fq%3Dgreen%2Bstriped%2Bmapleworm%26start%3D20%26gbv%3D2%26ndsp%3D20%26svnum%3D10%26hl%3Den%26rls%3DDNUS,DNUS:2006-36,DNUS:en%26sa%3DN

The left one....a Variable Oakleaf caterpillar.

http://images.google.com/imgres?imgurl=http://www.forestryimages.org/images/192x128/2733042.jpg&imgrefurl=http://www.forestpests.org/georgia/defoliators.html&h=128&w=192&sz=11&hl=en&start=7&tbnid=2Oedq1HFK_88dM:&tbnh=69&tbnw=103&prev=/images%3Fq%3Dvariable%2Boak%2Bcaterpillars%26gbv%3D2%26svnum%3D10%26hl%3Den%26rls%3DDNUS,DNUS:2006-36,DNUS:en%26sa%3DG

Neither of those are the tent caterpillar types. Well done on shaking some loose!

Still, catharsis is good.

fly_girl, I think you are correct! Sure looks right to me. Thanks for the links.

Viburnum, I believe it's called OCD. LOL!

Edited to add: I forgot to mention that, in doing some caterpillar research, I read several times that the caterpillars may be worse after the trees have been stressed. We had a very bad (worst I've seen in my lifetime) hail storm in early March followed by a late freeze on Easter eve. The trees were all leafed out and killed by the freeze. It's been an unusual year for pests - every shovel of soil has had 2 to 4 grub worms and we had a leafhopper 'plague' a few weeks ago. So thick I had to turn my windshield wipers on one night driving home after dark. Between the hail, freeze, grubworms working on the roots and the leafhoppers working on the upper plant........it's a wonder we have anything living at all!

This message was edited Jun 28, 2007 8:02 PM