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Caterpillars on Azalea Plants: Identification and Control (With Photos)

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Caterpillar Pests on Azalea Plants

When it comes to caterpillars that eat azalea leaves, there's really only one culprit: Datana major, AKA "The Azalea Caterpillar." Most caterpillars only eat one kind of plant, and this species has become a specialist in attacking, and often destroying, cultivated azaleas. This brief but comprehensive guide covers identification and control of D. major, so you have a chance of stepping in and saving your plants from possible destruction.

Adult azalea caterpillar (Datana major)

Adult azalea caterpillar (Datana major)

Azalea Caterpillar Description

You will often find immature and mature azalea caterpillars together. This is because several moths will lay eggs on one plant at different times, creating multiple broods living together. The smaller ones will eat until they are eventually the same size as the big ones; at that time they begin the process of transforming into the adult moth ("pupation").

Immature azalea caterpillars are very small, often less than 1/2 of an inch long. At this point in their development they are nearly impossible to find, especially since the leaf damage from their feeding is minor and not really noticeable. These tiny caterpillars will be found in a group. They are dark red-brown with faint pale stripes.

Datana major caterpillar in typical pose

Datana major caterpillar in typical pose

Mature Azalea Caterpillar Identification

As they grow, they begin to become more noticeable, and more easily identifiable. Mature azalea caterpillars are about two inches long and distinctly colored, with a red ground color contrasting with bright yellow longitudinal stripes that are more or less broken up to resemble spots in some individuals. They have a large, bright red head, are found in groups, and have a habit of throwing up their head and tail when disturbed revealing red legs and underside in a kind of threat display.

There is really no other caterpillar, on azaleas or otherwise, that looks like Datana major.

Datana major adult moth specimen

Datana major adult moth specimen

Adult Datana major Moths

The adult moth, the one that laid all of the eggs on your azaleas and gave you a potentially destructive infestation, is actually quite subtle and pretty. They are part of a large group, the "prominents" (family Notodontidae), that includes some absolutely gorgeous moths, and correspondingly striking caterpillars. Datana major itself has several close relatives which it closely resembles, although none of them are pests on azaleas (some are pests on other plants and trees).

The adult moth is well-camouflaged among brown leaves and twigs, with its "leaf vein" markings and disruptive red-brown thorax coloring.

Datana major adult moth at rest, showing cryptic coloring

Datana major adult moth at rest, showing cryptic coloring

There is really no other caterpillar, on azaleas or otherwise, that looks like Datana major.

Records of Datana major in North America

Records of Datana major in North America

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Range of the Azalea Caterpillar

As the above map shows, D. major is a primarily eastern and southern species. This means that the caterpillar is most likely to be a pest on your azaleas if you live in this general zone; however this is by no means a hard and fast rule, and with the added influence of a warming climate, you may experience an infestation well out of the range described here.

If it looks like an azalea caterpillar, and it's on your azaleas, then that's what it is, even if you live in Wisconsin!

Gorgeous azaleas

Gorgeous azaleas

Azaleas as Garden Plants

Azaleas are a kind of flowering rhododendron, well-known for their beautiful blossoms. They are tolerant of shade and can be found in flower beds and landscaping across the American South and well into northern areas. There are over 10,000 cultivars, including a range of colors from hot pink to white, including coral, fuchsia, purple, orange, and red. There are also multi-color varietals.

Azaleas are typically spring-bloomers, although in the deep south they may also flower in the fall. Because of their shade tolerance, azaleas are often planted under trees. They grow slowly and prefer acidic soils.

Azalea caterpillars typically feed in a group.

Azalea caterpillars typically feed in a group.

Control of the Azalea Caterpillar: The Simplest Solution

Since Azalea caterpillars typically feed in a group, and are so easily identified and spotted, the simplest and most effective way to control them is to put on your gardening gloves, pick them off by hand, and drop them in a bucket of soapy water. Or, if you have chickens, they would no doubt love a meal of these fat, nutritious caterpillars. Either way, the quickest and most environmentally responsible approach is to physically remove them.

(When I was young, a neighbor paid me a nickel for every tomato hornworm caterpillar I could remove from her vines. If you're squeamish about grabbing azalea caterpillars, you may want to use the same approach with youngsters in your neighborhood).

Diatomaceous earth can help control azalea caterpillars

Diatomaceous earth can help control azalea caterpillars

Control of the Azalea Caterpillar: Diatomaceous Earth

Diatomaceous earth, for the uninitiated, is a non-toxic, 100% natural substance that is used to control caterpillars and other soft-bodied insect pests. It's actually a kind of dirt with a high content of fossilized diatom shells. These microscopic, glass-like shards damage and destroy insects as they crawl over them; there are no poisons or toxins involved. In fact, most diatomaceous earth sold online is "food grade," meaning it's safe for humans to consume if they wanted to.

Resources

https://blogs.ifas.ufl.edu/jacksonco/2020/07/27/controlling-azalea-caterpillars-on-azaleas-blueberries/

https://ugaurbanag.com/azalea-caterpillar-datana-major/

https://content.ces.ncsu.edu/insect-and-related-pests-of-shrubs/pests-of-azalea


This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

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