‘Labor Day Worms’ Seem to Be Arriving Earlier This Year

— Written By and last updated by Diane Lynch

Q: What are these black and yellow caterpillars eating on my azalea leaves?

A: The worms being described sound like azalea caterpillars. In the past couple of weeks, we have had several questions and samples brought in of azalea caterpillars. Often referred to as Labor Day worms, these caterpillars usually show up on azaleas around late August and early September. This year, it appears they are showing up earlier.

As with other caterpillars, eventually these “worms” turn into a moth. The adult moth begins flying about in early summer and deposits its eggs in masses of 80 to 100 on the underside of azalea leaves. The eggs become the azalea caterpillar. Young azalea caterpillars are small, green caterpillars that grow into purple and yellow-striped caterpillars. These young caterpillars will molt into large black and yellow-stripped worms with red heads and legs. When a caterpillar is disturbed, it will raise its head and tail to curl backwards in defense.

The caterpillars cause damage to azaleas around late August into September. When the eggs hatch, the caterpillars damage azaleas by eating leaves and can completely defoliate limbs. Because the caterpillars feed in groups, they are often not detected until a portion of an azalea is severely defoliated.
There are a couple of options for controlling azalea caterpillars. One control option is to pick the caterpillars off (don’t worry, they are harmless to humans) of azaleas and discard in a bucket of soapy water. Another option if there are just a few caterpillars or a few azalea shrubs is to shake them from the shrub and step on the caterpillars to kill them (that is if you do not mind the idea of squishing a caterpillars). B.t. (Bacillus thuringiensis) is an organic option that can provide control of young caterpillars. B.t. is usually marketed under the name DiPel. If you choose to control with insecticides, Sevin (carbaryl), Orthene (acephate), and pyrethrin-based insecticides should give adequate control. When using insecticides the best control is achieved by applying when caterpillars are first noticed. Only spray an insecticide if you discover azalea caterpillar on your azaleas. Trying to spray when the treatment is not needed would only be a waste of time and money. As with all pesticides, remember to read and follow all label directions.

As you are working in the landscape this time of year, take the time to do some scouting for the azalea caterpillars that could be lurking in your azaleas. Catching these Labor Day worms early, can allow for better control and prevent defoliated azaleas.

For your gardening, landscape, and lawn questions contact the Wayne County Extension Master Gardener Volunteer Plant Clinic on Mondays and Wednesdays from 10 am to 1pm. The plant clinic is a free service open to any citizen in Wayne County that has home gardening questions. One can reach the Wayne County Extension Master Gardener Volunteer Plant Clinic by phone at 919-731-1433, e-mail at Master.Gardener@waynegov.com, or stopping by Room 100 of the Wayne County Extension Office (208 West Chestnut Street, Goldsboro). People contacting the plant clinic with questions are encouraged to bring samples and/or pictures that could help in reaching a solution. Extension Master Gardeners are trained volunteers with the Wayne County N.C. Cooperative Extension Service.

Recommendations for the use of chemicals are included in this article as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services does not imply endorsement by the North Carolina Cooperative Extension Service nor discriminated against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical. For assistance, contact an agent from North Carolina Cooperative Extension Service.

Learn More!
• Visit our website at https://wayne.ces.ncsu.edu/. Click on “Lawn & Garden” on left side of webpage.
• “Like” us on Facebook to receive timely garden tips, ask questions, and learn of upcoming gardening events. www.facebook.com/waynecountygardening

Upcoming Local Gardening Events:

• National Honey Bee Day Celebration on Saturday, August 17th from 9am to 1pm at Waynesborough Park. Admission to the celebration is free and open to the public. The celebration will include information about beekeeping and importance of honeybees. Observation hives, beekeeping equipment, candle making and honey sales will be on site along with beekeepers who can answer your questions. Children activities and food vendors will also be available during the celebration. The celebration is hosted by Beekeepers of The Neuse.

• “Knowledge to Garden” Fall 2013 Workshop Series. The Wayne County Extension Office will be offering workshops featuring two gardening topics in various locations and times this fall. All classes are free and open to the public. Registration is required by calling the Wayne Co. Extension Office at 919-731-1520.
Growing a Fall Vegetable Garden

  • Tuesday, August 20, 4:30 to 6:30pm at the Wayne Co. Public Library, 1001 E. Ash Street, Goldsboro
  • Thursday, September 12, 3:30 to 5:30pm at the Fremont Public Library, 202 N. Goldsboro Street, Fremont

Backyard Composting

  • Saturday, August 24, 10am to noon at the Wayne Co. Extension Office, 208 W. Chestnut Street, Goldsboro
  • Thursday, September 12, 10am to noon at Mount Olive College, Hennessee Room (adjacent to cafeteria in Lois K. Murphy Regional Center), 630 Henderson Street, Mount Olive

NCSU & NC A&T University commit themselves to positive action to secure equal opportunity regardless of color, creed, national origin, religion, sex, age or disability. In addition, the two Universities welcome all persons without regard to sexual orientation.

Jessica Strickland
Extension Agent
Horticulture
North Carolina Cooperative Extension
Wayne County Center
P. O. Box 68
Goldsboro, NC 27533
E-Mail: jessica.strickland@waynegov.com
Phone: 919-731-1525
Fax: 919-731-1511
https://www.ces.ncsu.edu/wayne

Written By

Photo of Jessica StricklandJessica StricklandExtension Agent, Agriculture - Horticulture (919) 731-1521 (Office) jessica_strickland@ncsu.eduWayne County, North Carolina
Updated on Aug 20, 2013
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