With the cooler mornings and evenings of September, one can spend extended time outdoors. While checking my azalea beds, I noticed several denuded branches. The culprits were clustered together at the top of one bare branch—three red headed yellow striped robust caterpillars.
Azalea caterpillars, Datana major, emerge from tiny pearl-white eggs laid on the underside of leaves early in spring by a nondescript brown moth with a wingspan of two inches. In late spring, 1/2” long caterpillars with reddish to brownish body, black head, and seven yellow or white longitudinal stripes down the sides hatch and start chewing azalea leaves.
As they eat, they grow and molt. With each instar the caterpillar changes color and pattern. The mature larvae on my azaleas were 2” long with black body, bright neon yellow dashed lines of longitudinal stripes, crimson legs, and a big round red head. The body of the caterpillar is studded with white hairs. These hairs are harmless to humans.
The fine white hairs on the body area defense mechanism used to warn predators. The hairs pose no harm to humans.
My captive caterpillars had to endure a physical exam before bidding them adieu. I touched the critters and saw their characteristic caterpillar response of arching head and tail up to form a U-shaped body. On the underside there are three pairs of true legs on the thorax and four pairs of prolegs on the abdomen. The true legs were curved and pointed like claws. The prolegs look and act like suction cups. At the rear of the caterpillar is a pointed red clasper. A child’s plastic magnifying bug jar allows close viewing of all kinds of garden insects.
This caterpillar trio was in the final instar and destined to be nearing the pupal stage. Pupas overwinter underground in a soil chamber until spring when the adult moth emerges, and the life cycle resumes with laying of eggs and immature larvae skeletonizing leaves and mature larvae defoliating shrubs.
My organic method of pest control for these critters is to pick off by hand and squish with my shoe. Resident birds have probably been picking their share this summer too. There is no need to treat this pest with an insecticide.
Azalea caterpillars can denude a shrub but rarely do they kill it.
Azalea caterpillars prefer Rhododendron indica in the southern U.S. and Andromeda polifolia in northern states but have also been reported on apples, blueberries, and red oaks.
After doing a thorough scouting for pests in all azalea beds and finding no more red heads among the leaves, I recorded the findings in my journal and made a calendar note to check the indicas for eggs in early spring to prevent the cycle from continuing. Since red heads love azaleas, get out and scout your indica today.
The azalea caterpillar bends its head and rear end into a Ushape when touched.
A mature azalea caterpillar pupates in an underground chamber in fall to emerge as a moth in spring.
A child’s bug magnifying jar gives a close view to all your garden insects.
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