Will silkworms kill a young mulberry tree?

We’ve been watching silkworms developing with fascination but today my thoughts turned to concern for our small tree as the worms are taking over more and more branches and eating every leaf until it’s gone. Will it continue until there’s none left? Will the tree survive?

Hi Sarah,

The catipilars have appearantly already eaten half your trees, which is stressful enough on the tree. Meanwhile the catipilars are growing larger and more ravenous every day, so the time it will take the catipilars to finish off the trees, will be much quicker then the first half they already defoiliated. Yes young trees can be severely damaged from pest problems, as observable in your pictures, and trees can even die off from such pests. Even if the trees dont die from the immediate stress of the slow and complete defoiliation, its still possible the weakend tree may perish in over wintering, since the limited energy stores can cause the trees not to survive the harshness of the winter season, to successfully leaf out when spring bud break arrives.

Hope that helps.

Thank you. That makes a lot of sense. Any idea if we can move them from our cultivar to one of the "wild" mulberry trees in the area? There are a lot around us...

Sarah Milcetic wrote:Thank you. That makes a lot of sense. Any idea if we can move them from our cultivar to one of the "wild" mulberry trees in the area? There are a lot around us...

Perhaps use them as fishing bait?

Do you know what type of silkworms these are?

r ranson wrote:Do you know what type of silkworms these are?

I don’t know. This is the first time we’ve seen them. Here’s a couple closer photos if that helps?

These look like tent caterpillars to me.  But I don't know the bugs in your region so they could be a type of silkworm I haven't encountered (there are about 198 different varieties of known silkworm I haven't met yet, so this is very possible).  bugguide is a great place for insect ID, they usually tell me what it is within a couple of hours.  Awesome people!

The wild silkworms I know don't make much silk until they cocoon.  Maybe test a bit of the 'tent' to see if it is strong.  The individual threads should be almost as strong as a hair from a healthy human.  

My son has interacted with them more than I have and he thinks they are as strong as a hair. I will follow your link and try to learn more. Thank you!

Sarah Milcetic wrote:My son has interacted with them more than I have and he thinks they are as strong as a hair. I will follow your link and try to learn more. Thank you!

I saw something on those a while back. A BAD caterpillar from what I can vaguely remember.

About an inch long I think and many times they hang from a single silk thread towards the ground.

Just can't remember the info on them.

Hi Sarah,

Im not a silk worm expert, but they do look to me like tent catipilars, as was already mentioned. Tent catipilars are very destructive, and can wipe out entire trees with infestations that can be wide spread throughout a local region. You might think your helping the catipilars, but if you let them mature, those very catipilars once mature, will be laying enough eggs to seriously damage many large trees. Tent catipilars are like locust, and can cause massive destructive infestations left unchecked. The butterfly effect of that little colony, could be destroying entire food forests next summer, and since they are typically protected up high in large trees, they are often hard to treat without specialized equipment.

I think they look like tent caterpillars also...we usually remove with a long stick, twisting the web like cotton candy and just leave on the ground elsewhere as I've heard they won't survive without the tree leaves and won't crawl back up.

They are always on the wild american persimmons here, way high in the tree and those trees seem to survive just fine...smaller, younger trees are more stressed by them.

I don't know silk moths at all though and am wondering how these were ID'd?

We watched more and talked to a neighbor who is a botanist and nature observer and he agreed they are/were tent caterpillars. We had seen the mature moths last year in area parks but I had read that they start their tents at the branch crotches and these all started on the tips. Our neighbor said he had only ever seen them on redbuds in the area before but we also noticed them on a very large mulberry tree in town. We knocked them all down to the ground and will keep checking the area. They were trying to move to our nearby bee balm and our rose that makes the best hips. Seems like they would eat anything they can reach! Yikes!

The mulberry tree put out a new set of leaves and seems to be doing okay. We found more tent caterpillars on a quince and caught it earlier this time...