Cankerworms

Print
 
Cankerworms

Rock Hill has an infestation of an inchworm (a type of caterpillar) known as cankerworms.  There are 2 species of cankerworms, and we have both of them - Fall cankerworm and Spring cankerworm.  Since both species are responsible for the defoliation of entire trees in the springtime, and the controls are the same for both species, for clarity and simplicity we will refer to these insects as cankerworms and our recommendations will be the same for both species.

 

 

 

NOVEMBER 2013

Tree bands installed on some street trees ( photo taken prior to applying Tanglefoot to bands).

 

DECEMBER 12, 2013

Adult cankerworm moths are beginning to emerge in Rock Hill.  These are Fall cankerworm adults, the first of 2 cankerworm species to emerge in Rock Hill, and emergence will continue over several weeks, probably into late January or early February.  The adult moths of the second species, Spring cankerworm, will begin to emerge with the onset of warm weather in March, and that emergence will last for a few weeks.  This is why we are advising to leave your tree bands in place until late April, and then remove them.

The following photos from trees banded on Dave Lyle Blvd on 12/12/13.

 canker2

 

This should give an idea of the relative size of the cankerworm moth adults:

 canker3

 

 

Below is a photo of the adult cankerworm moth on the bark of an oak tree.  There is also an egg mass toward the upper right corner of the photo:

 canker4

 

 

 JANUARY 23, 2014

 When driving on Dave Lyle Blvd (photo is from entrance ramp) it is difficult to tell how full the traps are becoming.  The insects have emerged in recent weeks in high numbers, and folks that have banded their trees are noticing good results in their traps (sticky bands).

 dlramp

 

Below is a closeup of one of the traps in the above photo, with adult male cankerworm moths, adult female cankerworm moths and eggs - all in the same trap.  IT IS IMPORTANT TO LEAVE THESE TRAPS ON THE TREE UNTIL AFTER THE EGGS HATCH, SO THE INCHWORMS ARE TRAPPED WHEN THEY HATCH OUT.  Leave the sticky bands on the trees until the end of April 2014, and then please remove them.

 moth

 

 

Below is a photo of a very successful tree band that has trapped thousands of adult female cankerworms so far.  Each trapped female represents between 100 and 150 eggs that hatch out into inchworms . . . millions of inchworms prevented by this single, well executed tree band!

canker5 

 

 

 The photo below shows exactly what cankerworms are hardwired to do: lay their eggs close to the food source.  The eggs are small, but you can see them with your naked eye.  This twig came from the canopy of an oak tree in Rock Hill that was removed in February 2014.

eggs

 The purpose of banding trees in the fall/winter is to prevent this from occurring!

 

WEDNESDAY, MARCH 26, 2014

Today we found the first physical evidence of cankerworm eggs starting to hatch out.  The photo below was shot on a tree band on Dave Lyle Blvd, and you can see (barely - these are TINY in real life on the bands) young cankerworms caught in the sticky Tanglefoot material.  It will take about a week for them to grow large enough for folks to begin to notice them, and then they'll be around for about 4 weeks.  It looks like the main season for the inchworms in Rock Hill will be the month of April. 

 

FOLKS WHO INTEND TO SPRAY THEIR TREES SHOULD SCHEDULE THIS WORK SOMETIME DURING THE FIRST 2 WEEKS IN APRIL.  The "effective spray window" is very short for caterpillars like these!

 

eggs2
 

 

 

TUESDAY APRIL 1, 2014

Not an April Fools prank, unfortunately.  We're finding cankerworms on the newly emerged leaves of some ornamental cherry and pear trees.  These little guys are still too small for most folks to notice them, that probably won't happen until next week sometime.

leaves 

 

Can you see the tiny cankerworm eating the edge of the leaf near the middle of the photo?

 leaves2

 

This one is rappelling down on a silken thread.  The inchworms must be tremendously mobile this way, given how blustery the weather can be can be this time of year.

 

APRIL 16, 2014

Cankerworms, their webs, and feeding damage to trees has been evident in Rock Hill in many locations for a week or more.  We have another couple of weeks before these insects will move on to the next stage of their life cycles (pupae, underground) where they will be out of sight and out of mind for most of us until late fall/early winter, when we will need to band our trees once again to try to limit their numbers.  Right now is pretty much the end of the "effective spray window" in Rock Hill, as these worms are growing too large to be easily controlled with insecticides.  For folks with a heavy infestation, at this point it may be best to just endure them and start making plans to band your trees in the fall.

We've had some questions on the variety of colors . . . cankerworms here seem to be either all green, all black, or green with black stripes (lengthwise).  The photo below shows the black color phase.

leaves3

 

 

 The next photo shows a green cankerworm eating leaves of willow oak that are just emerging and beginning to expand.  The timing of cankerworms of this size eating newly expanding leaves is VERY damaging to trees, because the cankerworms can eat all the new leaves off the entire tree before they get a chance to expand!  One of the benefits of banding your trees, even if it doesn't completely prevent cankerworms from infesting it, is that IT SLOWS DOWN the rate of defoliation and allows the leaves to more fully expand and harden off.  So it does help your trees, even if it doesn't seem like it did much to reduce the cankerworm population.  This photo shows the worse-case scenario:

leaves4

 

There are animals that do feed on cankerworms.  Many species of birds, some lizards, mammals and even other insects feed on cankerworms.  This photo shows a predacious beetle (slightly out of focus) hot on the trail of a cankerworm on the same leaf!

leaves5

 

Please remember to remove the bands from your trees at the end of April.

 

 

 

CANKERWORM LINKS

The following links should open various pdf documents that are printable.

Cankerworm fact sheet

General Information on Banding Trees

Detailed D-I-Y Tree Banding For Cankerworms

Spray Options for cankerworms

 


 

 

 

           VIDEO FROM OCTOBER 10, 2013 TREE BANDING WORKSHOP

 

The page below is a list of other web sites that provide additional information about things like, where to find tree banding supplies if Rock Hill vendors run out, how to organize your neighborhood association to band trees, etc.

 

Cankerworm-Related Web Sites