What Every Homeowner Needs to Know About Their Aging Trees

Where did all the Cankerworms go in the spring of 2019


 Cankerworm Page

Info Spring 2008

May 27, 2008

I stopped writing about the time the city sprayed the trees.  In my neighborhood which is Myers Park I think the spraying was about 98 percent effective.  There is always some damage to tree foliage.  It could be young squirrels sharpening their teeth or a severe wind storm that rips away foliage.

I did see some healthy looking cankerworms caught in my traps a week or so after the spray, so it did not get them all.

As I look up in the canopies I can not see any damage.  As noted below there is some damage to under story trees.  I have since heard that in areas where there was no spraying, there was a lot of defoliation.  In particular I think the Ballentine area was hit pretty hard.

It will be interesting to see what the city does for this next year.  Banding in the fall will tell us how much insect activity there is and I suspect that it will be small.

This should be the last report until fall.

jack mcneary


April 16, 2008


On my way home on April 14, I decided to stop my car near some small willow oaks that were either late coming out or were being eaten by something.  I stopped on Queens Road West near Hopedale where there were three or four small willow oaks in among the larger willow oaks along the street.

There was  much defoliation and lots of webs.  Later the next morning on the 15th I drove to another location and found similar feeding.  The insects feeding were longer, bigger, fatter than the ones I have been seeing on the traps.  On the traps, the insects are small, shriveled, dead, writhing, or otherwise not doing much.  Of course there is nothing on the trap for them to feed on.

My conclusion is that these smaller willow oaks are under story trees and I think the following things occurred.

1. The spray mist never got to these trees because it was all (or most) trapped by the canopy’s of the larger trees.
2.  By the time the mist got down to the affected trees, it did not stick to the leaves because it already had dried up.
3.  Spraying just missed that entire area.  This is not likely because I think the larger trees have come through pretty well. 

Had  the spray not been affective, NOW is the time we would be seeing lots more webs and lots of vigorously crawling insects.  We would be having caterpillar frass (droppings) all over our cars and in my case a slate front porch.  We would also be seeing major reductions in canopy of the willow oaks like we saw last year.

We have another week to go to really tell, but I am still prepared to put on more Tanglefoot if needed and for that matter spray the trunks of the larger trees and some shrubbery that the insects like to feed on.

April 14, 2008

I suppose I should start by saying I was a little pessimistic about the outcome of the spray program.  Things went better than I expected.  I was under the impression that they would use fewer planes and it would take longer.  Had that been the case, then I did not think they could have such good weather.  If I was wrong that is good for the trees and the people who live in Charlotte.

Today is Monday, and spraying for the fall cankerworm started exactly one week ago.  I understand that five airplanes were involved, and we saw them flying overhead on both Monday and Tuesday.   It seems at this time although it is a little premature that the spraying worked pretty well.

I am basing that on a number of observations.  The conditions were quite good for spraying in that there was little wind, no rain, and the relative humidity was excellent.  The mist that is used needs to coat the surface of the leaves and buds that the caterpillars will eat.  It does not take much material for them in ingest before it affects them.

I saw my first cankerworm suspended from its silken thread on Monday and it was about 3/8th or an inch long.  It was hard to tell if it was healthy or not.  In the past I have seen them writhe and spin around when they were under stress from the spray.  There were a few other small cankerworms in the main trap on my willow oak. 

By Thursday, I counted approximate 500 small cankerworms in the trap.   These worms were in the early stages of growth and were of various sizes.  Most of them seemed dead and very lifeless.  The largest worm might have been 5/8th of an inch long.

There have been some webs, but not like years past. I think the worms we are seeing are ones that have bailed out of the tree on their silken threads.  Usually, what we think happens is that they have eaten their fill or the wind blows them out.   As I look up in the trees I see full canopies.

The insects caught in the traps are mostly green and not striped.  They are small and most are barely moving.  A few are slowly crawling up the tree trunks from the ground.

So, are we finished with the cankerworms forever?

I suspect that pockets will show some defoliation.  Certainly, the technology is much better.  The pilots have GPS, better weather predictions and better machinery to apply the pesticides.

I will wait until next week to decide how effective the spray was.  So far it looks promising. 

If you start to see cankerworms crawling up the trees in large numbers and if they look like they have a purpose, then get some more Tanglefoot around the existing band.

       April 1, 2008

The first Current Stuff page started with the migration of the fall cankerworm in 2007.  Since that page was getting pretty long, I thought it time to move along to follow the spring hatching of the insects and their movements throughout the spring.

The new date will be at the top of the page, and you will have to scroll to the end of the page to read the comments from April first on.

Today it is cool, 50 degrees, cloudy and still drizzly,  It has been that way for a few days with little total volume of rain to help the drought. but it is allowing the flowers and trees a nice start for spring.  Since it is helpful to know when and what causes certain insects to hatch, I plan to also mention other things that are in bloom.  This way when the next season approaches we can see what triggers the cankerworm and for that matter other insects and weeds.

Many plants and insects go through a dormancy during the winter and start doing their thing due to a number of different variables.  Some plants and insects have to have a certain number of daylight hours to start flowering or breeding  This is referred to as Degree Days.  We often think that warmer days and nights cause the break in dormancy, but often there are a lot of other factors.  In some seeds, for instance a tomato seed has a slimy coating over the seed.  This inhibits the seed from germinating as soon as it falls from the plant.  If you remove that coating with your fingers, the seed will germinate immediately.

In the case of the cankerworm, it seems to like the willow oaks more than any other type of tree in our area.  In other parts of the country trees such as the elm are the favorite target.   On a similar note, a cold winter seems to have no bearing on killing off the female cankerworm.  Some of the worst infestations in North American are up on the border of the US and Canada.

From nature’s standpoint, it would not be good for the cankerworm to emerge before the willow oaks start to put out their leaves.  There would be nothing to eat.  From some past records, it seems the cankerworm hatched in March.   to be continued.

New information will be added to the top of this page.  When you log in, you will be at the top of the page and will have to read downward to get to the beginning.  In this case the beginning is Spring (April ) 2008.