Azalea Caterpillar: All You Need to Know for a Healthy Garden

Azalea caterpillars are a common pest that can cause significant damage to azalea plants.

These caterpillars feed primarily on the foliage of azaleas, leading to defoliation and eventually stunted growth or even plant death if left unchecked.

To identify azalea caterpillars, look for:

• Black and yellow striping on their bodies
• Red or orange heads

Some key characteristics of azalea caterpillars include:

• Fuzzy appearance due to their long hairs
• Active during late summer and early fall
• Rapid increase in size, as they can grow up to two inches long in just a few weeks

Before considering pest control methods, it is vital to understand the pros and cons of each approach to ensure the safe and effective management of azalea caterpillars.

Azalea Caterpillar Basics

Identification

The Azalea caterpillar, scientifically known as Datana major, is a colorful and distinct species. Its appearance changes as it matures:

• Immature caterpillar: Crimson-colored with a black head
• Mature caterpillar: Black and yellow with reddish-brown head and white, broken longitudinal stripes

These caterpillars can grow up to 2 inches long.

Habitat

Azalea caterpillars are primarily found on azaleas and rhododendrons. Most states that have these plants will have these caterpillars as well.

Life Cycle

The Azalea caterpillar goes through a life cycle typical of moth species:

1. Moth: Adults emerge, usually brownish-black with yellow stripes.
2. Eggs: Female moths lay eggs on the underside of leaves.
3. Larvae: First-instar caterpillars hatch, initially red-headed and then changing colors as they mature.
4. Pupation: Mature caterpillars pupate and transform into adult moths.

Azalea caterpillars have one generation per year. Bacillus thuringiensis (Bt) can be used as a biological control method to limit their population growth.

Host Plants and Damage

Commonly Affected Plants

The main host plants for azalea caterpillars are:

• Azaleas (Rhododendron spp.)
• Oak trees
• Blueberry bushes

These plants are more likely to be targeted by the caterpillars, especially during their growing season.

Symptoms of Infestation

Indications that azalea caterpillars have infested a plant include:

• Leaves with chewed edges
• Defoliation, or loss of leaves
• Presence of small green or larger black and yellow-striped caterpillars on the underside of leaves

For example, infestations often go unnoticed until a significant amount of damage has been done.

Impact on Plant Health

Here is a comparison table of the impact of azalea caterpillars on different plant aspects:

The main concern with azalea caterpillars is the damage they cause to the leaves, resulting in defoliation.

While they usually do not kill the host plants directly, the stress resulting from this extensive leaf loss can weaken the plants and reduce their ability to produce flowers.

Lace bugs may also infest the same plants, adding to the damage caused by azalea caterpillars.

Prevention and Control Measures

Natural and Biological Control

Azalea caterpillars are most commonly found in late summer to early fall, feeding on azaleas and other plants like blueberries and Andromeda.

These pests are considered gregarious since they usually cluster together while feeding.

One natural and biological way to control them is introducing predatory or parasitic insects, such as:

• Ladybugs
• Lacewings
• Parasitic wasps

These insects are harmless to humans and help reduce the number of azalea caterpillars present in your garden.

Cultural Practices

A few cultural practices can help prevent the infestation of azalea caterpillars, such as:

• Regular inspection: Keep an eye out for eggs, which are a sign of an incoming caterpillar infestation.
• Physical removal: If you spot small clusters of caterpillars, manually remove them from your plants, being careful not to harm the plant itself.
• Proper care: Ensuring your plants receive adequate water, soil nutrients, and sunlight can reduce their stress levels, making them less susceptible to pests’ damage.

Chemical Control

When severe infestations occur and other methods are not effective, you may consider using chemical control to manage azalea caterpillars.

Conclusion

Azalea caterpillars are colorful and hairy caterpillars that belong to the sphinx moth family. They have black and yellow stripes, red heads, and black spots on their backs.

They are found in the southeastern United States, where they feed on azalea leaves. They hatch from eggs in late summer and go through five instars before pupating in the soil. They emerge as moths in spring.

They can cause defoliation on Azaleas if they occur in large numbers. They can be controlled by hand-picking, pruning, or using biological or chemical pesticides.

Azalea caterpillars are interesting and attractive insects that add beauty and diversity to the natural world.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about Azalea caterpillars. Scroll down to have a look at some of them.

Letter 1 – Azalea Caterpillar

black and white stripped caterpillar
December 24, 2009
I found these acrobatic caterpillars on my George Tabor Azaleas I believe it was in September. Their black and white stripes were quite different. It was their red head and legs and tail that caught my attention.

No major harm was done to my azaleas. Could these be the caterpillars for a zebra swallowtail?
Leslie
Saint Fancisville, La

Hi again Leslie,
These are Prominent Moth Caterpillars in the genus Datana.  It is probably the Azalea Caterpillar, Datana major, which feeds on Azalea and a few other plants including red oak, apple and blueberry. 

The species is well represented on BugGuide which indicates:  “female lays masses of 80-100 eggs on underside of leaf in late spring or early summer; first instar larvae feed gregariously, skeletonizing leaves of hostplant; older larvae eat entire leaves; usually one generation per year, with partial second generation in the south; overwinters as a pupa in a cell in the soil.” 

This posture is typical of caterpillars in the genus Datana.

Letter 2 – Azalea Caterpillars

Caterpillar identification needed
Greetings,
Today I discovered a cluster of caterpillars on a Pieris Japonica at my home here in Raleigh, North Carolina. I’m a school librarian (aka “media specialist)” and I plan to bring in a couple of these “specimens” to show the students at our school, Brassfield Road Elementary.

Naturally the display would be more educational if I could identify them. I didn’t find a match in my small field guide at home, and I was so impressed with your web site, I thought I’d defer to your expertise. Thanks so much for your help with the identification,
Vicki Sanders Corporon
Raleigh, NC

Hi Vicki,
These are Azalea Caterpillars, Datana major. According to BugGuide, in addition to azalea leaves which they prefer, they “have also been recorded on apple, blueberry, Red Oak, and Bog Rosemary (Andromeda polifoloa ).”

Letter 3 – Azalea Caterpillar

beautiful caterpillar
My husband and I found this on a blueberry bush. As soon as we touched the branch, “he” assumed this defensive posture, curling up and emitting a drop of liquid from end back end.

It’s a beautiful creature, but what is it? I’m sorry but I wasn’t able to place the photo into this e-mail, other than attaching it. I hope you are able to open the document. Thank you
Sarah, Rolla, MO

Hi Sarah,
Despite being named the Azalea Caterpillar, BugGuide indicates that Datana major can also be found on blueberry.

Letter 4 – Azalea Caterpillar

Mean looking caterpillar
Greetings Bugman,
I live in Tallahassee, FL and I recently found these very agressive caterpillars all over a bush in my front yard. If you prod them with something, they arch their back and lunge at whatever touches them, while simultanously regurgitating some green goop and smearing it on whatever touches them.

They have 3 sets of segmented front legs which appear to have stingers protruding slightly from them, but I can’t really tell. A couple of days after I discovered them, they had all but disappeared leaving my bush in seriously bad shape.

I was fortunate to have received a new digital camera just in time to get some great macro shots of the last one I could find. I’m curous to know what it is and if it can sting. If it can’t sting, it sure can put on a good bluff!

Here’s the best shot I was able to get with my macro on a tripod….love my Nikon Coolpix 4500 macro for these types of shots!!
Brett

Hi Brett,
We didn’t have to research this Prominent Moth Caterpillar for too long before we located the Azalea Caterpillar, Datana major on this Florida website. The defense posture you describe as well as depict in your awesome photograph is typical of the entire Datana genus.

Letter 5 – Azalea Caterpillars, probably

Do you know what kind of caterpillar this is? They were on our blueberry bush!

These are caterpillars in the genus Datana.  Datana major, the Azalea Caterpillar is most likely and they appear to be early instars that will get more colorful as they grow and molt. 

You can read more about this species on BugGuide, where it is reported that they are sometimes found on blueberry leaves.  The posture and group grazing of this genus are quite unique.

Letter 6 – Azalea Caterpillars

4 ’Red Headed’ caterpillars grouped together
Location: Raleigh, NC
September 21, 2011 11:47 am
Hi Bugman,
I found out about you from a guy I work with. And thought that’s so cool!
The other day I saw that one of my azalea bushes was looking a little decrepit.

Upon further examination, I saw on a couple of branches, 3-4 caterpillars clumped together on each separate branch. Each caterpillar is 2-3 inches long at least a 1/4 inch in diameter. Mostly black, with sort of yellow stripes and red heads (or tails?)
Signature: Carolyn

Hi Carolyn,
Thanks for supplying the information that azalea is the food plant. 

nowing the food plant for a caterpillar makes identification so much easier, though in the case of these Azalea Caterpillars, Datana major, we have identified them enough times in the past to know what they were immediately. 

You can also view the BugGuide information page to learn more about this species that feeds in groups and often strikes a dramatic pose when it feels threatened. 

Letter 7 – Azalea Caterpillars

Subject: caterpillar
Location: south louisiana
July 10, 2015 12:38 pm
what is the name of a black & white caterpillar that has a red head and red feet
Signature: valentine

Dear Valentine,
These gregarious caterpillars are Azalea Caterpillars, Datana major, and according to Bugguide:  “larvae feed mainly on leaves of azalea (Rhododendron spp.) but have also been recorded on apple, blueberry, Red Oak, and Bog Rosemary (Andromeda polifoloa).” 

The Blue Jay Barrens blog has a very nice posting on the Azalea Caterpillar which includes this information:  “The hairs on this caterpillar serve no defensive purpose.  When threatened, the caterpillar raises its head and tail with thoracic legs thrust upward like horns. 

In addition to the threatening appearance, a bit of ingested material is regurgitated at the mouth and a droplet of liquid is released from the anus.  I’m assuming that both of these substances are unappealing in some way to predators. 

The anal droplet is visible in the photo as a honey colored sphere on the end of the upraised tail.  Quite an interesting little creature.”

Letter 8 – Azalea Caterpillars

Subject:  What’s this caterpillar
Geographic location of the bug:  Tallahassee, FL
Date: 08/04/2019
Time: 02:26 PM EDT
Your letter to the bugman:  Can you please ID this caterpillar?  There are tons of them under my life oak.  They’re eating my shrubs.
How you want your letter signed:  Thank you in advance, Michael

Dear Michael,
The arched posture these Caterpillars have assumed is typical of Prominent Caterpillers in the genus Datana, and we are pretty confident they are Azalea Caterpillars, Datana major, based on this BugGuide image. 

According to BugGuide:  “larvae feed mainly on leaves of azalea (Rhododendron spp.) but have also been recorded on apple, blueberry, Red Oak, and Bog Rosemary (Andromeda polifoloa).”  Are your shrubs azaleas?

Letter 9 – Azalea Caterpillar

Subject:  Caterpillar
Geographic location of the bug:  Northeast Alabama,USA
Date: 09/13/2021
Time: 09:43 AM EDT
Your letter to the bugman:  Several eating rhododendron leaves
How you want your letter signed:  Duck

Dear Duck,
This distinctive caterpillar is an Azalea Caterpillar, Datana major, and according to BugGuide:  ” As the larva matures it becomes highly colored. Mature larvae are predominately black with a red last segment and eight broken yellow (occasionally white) lengthwise stripes. The head and legs are bright red.”