Webworms invading Austin

I've been receiving calls on webworms that are in trees surrounding Ladybird Lake.  we also have webworms in a tree at the Demonstration Garden.  Since it's a demonstration garden, I'm using the webworms as a....you guessed it!....demonstration.

I'm sure that you have been told (even possibly by me) that you can manage webworms by removing webs and knocking them out the tree with a stick.  I decided to see how well it actually works.  So far, it's going pretty well.  I started two weeks ago when we had a pretty good covering of webs on the tree.  I took a metal pole (actually the handle of an insect net which I had in my office) and removed as much of the webbing as I could from the branches.  I made a pile of webbing and caterpillars on the ground while removing the webs and that got taken to the garbage when I was finished.  I also whacked on the tree branches a few times after removing as much of the webbing as I could to dislodge any caterpillars.  I repeated the process every Monday and Friday.  Today when I checked on the webworms, there was only one small new web spun very close to a small branch.  The rest of the area has dead leaves and some loose webbing clinging to the branches, but the webworms aren't actively there anymore.  I removed the small section of webbing I found today and whacked the branch.  I'll check the situation again on Monday.  While I'm not completely done with the demonstration, so far it is looking pretty good.
 

Webworms on 6/13/14

Webworms on 6/20/14

Webworms on 6/27/14



Webworms and a garden visitor

Webworm caterpillar.

This week-- tomorrow (May 3, 2014)- is the Travis County Inside Austin Gardens Tour.  The AgriLife Extension Demonstration garden is on the tour so our Master Gardener group has been working diligently to get things in top condition (and the garden looks great!).  A group was here on Tuesday and they asked me to come out into the garden to give a quick bug talk.  After we went on a field trip across the street to see a harvester ant colony and a leaf cutting ant colony I headed back to my desk.  Fortunately, a volunteer came in and asked me back outside to see what they found.

Webworm webbing.

In one of the trees, they had discovered webworms (see below for more information on webworms).  Not only were there webworms, but there was a Texas Spiny lizard sitting on top of one of the webs eating the caterpillars.  It was so incredibly cute!

The lizard after its meal.

Webworms are caterpillars that defoliate trees and cause large, unsightly webs on the tips of tree branches.  There are 2-4 generations of webworms that occur each year.  The first generation appears now and the last generation occurs in late fall.  The last generation tends to be the most damaging.

Webworm larvae, or caterpillars, are about an inch long when fully grown.  They are pale green to yellow with tufts of long hairs projecting from their body.  Most people notice webbing that they create on branches.  Webworms feed with in the webbing and use it as protection from predators.  When the caterpillars need new foliage to feed on, hey expand the web.

To manage webworms, try the following:

• prune eggs masses off before the caterpillars emerge (egg masses are on the underside of leaves and are covered with hairs from the adult moth)
• prune out small webs when they begin to form in the spring
• knock webs out of the tree with a stick or a high pressure jet of water; you can also open the webs with a stick or water to allow predators into the web
• look for products with active ingredients such as Bacillus thuringiensis var. kurstaki, spinosad, azadirachtin
• even when using a pesticide, you first must open the web to get the pesticide to where the caterpillars are located

Where have all the garden spiders gone?

I don't know about you, but I'm wondering where all the garden spiders are this year....I miss them! I'm sure that the weather and other environmental factors (that we're in a severe drought leading to less food availability) play into the fact that they seem to be non-existent in my yard this year. Usually, I have tons of these girls around the yard, one of which inevitability builds her web across my back gate so I walk through it when I go into the backyard.

The female garden spiders are easy to recognize with distinct webs. Garden spiders make the large webs with the "zipper" in the center. The spiders are fairly large (other than the males which are much smaller and often not seen) with yellow, black and white coloration.

These are great beneficials to conserve in the backyard habitat and help to cut down on garden pests. Of course, they are generalist predators and will pretty much eat whatever they capture; they don't have our knack for separating "good" bugs from "bad" bugs.

BB's update:

It's been awhile since an update on BB. BB is now 36 weeks along and should be arriving in about 3-4 weeks. Length is now around 20 inches and weight around 5.5-6 pounds. I, personally, am feeling huge and rather cumbersome. Getting up from a chair is becoming difficult and I have to take a break when walking up the stairs at home (ridiculous, I know). There's too much baby and not enough room at the moment, so I'm sort-of looking forward to when BB drops into my pelvis (other than the havoc he/ she will wreak on my poor bladder and the thought of waddling everywhere I go).

Something else I want to share is a picture of my hubby, Alan. He was working in Uvalde this week doing environmental assessments and found a tarantula. Of course, he couldn't leave it alone.....and yes, we're both a bit odd....

It's not fall yet, so why do I have fall webworms?

While I haven't been getting many questions on them, I thought I would address fall webworms since I've been seen tons of webbing in trees all over town. Webworms can attack over 88 species of plants, but are often seen on pecan trees in Texas. We have 2-4 generations each year that start in the spring and continue into the fall. Fall populations are often the most damaging, giving the name fall webworms.

Caterpillars, the immature state, are very pretty in my opinion. They are about an inch long when fully mature and are pale greenish-yellow with long tufts of hair projecting from their body. Adult moths are somewhat drab with whitish coloring and small, dark spots on the front wings.

When caterpillars emerge from the egg, they immediately begin to spin the webbing that is expanded to cover the tree's foliage. The caterpillars use the webbing to protect them from predators. They enclose the foliage that they feed on and will expand the web size when they run out of foliage to eat.

So, options for managing webworms really depends on how annoyed you may be with the webbing, how large the tree is and what kind of effort you want to give to manage the caterpillars. Egg masses can be pruned or picked off the tree (egg masses are on the underside of leaves and typically covered with hairs). Pruning webs out of the tree or opening the webbing with a stick or stream of water can also help to manage populations. Pruned webbing should be disposed of in a sealed, plastic bag or dunked in a bucket of soapy water to kill the insects. Opening the webbing can allow predators to enter the web and help manage the pests. You do not want to burn the webbing out of the tree as this can often cause damage to the tree as well as being dangerous.

Of course, there are also chemical options. Less-toxic options include using active ingredients such as Bacillus thuringiensis variety kurstaki, also known as Bt. This variety of Bt specifically targets caterpillars, but will not differentiate between "good" and "bad" caterpillars, so avoid drift. Spinosad which comes from a soil microorganism is another option. Both of these chemicals must be consumed for them to work properly, so good coverage of the foliage is key (hence, you must open the webbing to get the chemical to where the caterpillars are feeding!). These options work best on smaller caterpillars (less than 1/3 inch).

For management of larger caterpillars, contact kill chemicals work best. Some active ingredients to look for include permethrin, cyfluthrin, carbaryl or acephate. Again, the chemicals have to get into the webbing where the caterpillars are located or they will not work very well.

Of course, you can always choose to let the caterpillars do their thing. The trees and caterpillars have been here living together for many, many years and nature always seems to find a balance of things on it's own.

Also, don't expect webbing to disappear from the tree once the caterpillars are gone. You will either have to wait for a heavy rain or use a high pressure water stream to knock the web out.