Bacillus thuringiensis kurstaki
Bt (kurstaki)- Rate
- Label rate — ½–4 tsp per gallon on home concentrates; varies by product
- Best for
- Small caterpillars, if you cannot prune
Pest
Oleander caterpillar
Syntomeida epilais
The short answer
The orange caterpillar with tufts of black hair on oleander is the oleander caterpillar, and the blue-black, white-spotted moth with a red-tipped abdomen is its adult, the polka-dot wasp moth. Young caterpillars feed in groups and turn new shoots light brown; older ones eat whole leaves and, left alone, can strip a plant in as little as a week (UF/IFAS). Defoliation does not kill oleander. Snip off the infested tips while the caterpillars are small and grouped, and freeze them in a bag for 24 hours. Use Bt on small caterpillars if pruning is not practical.
hero macro · orange caterpillars with black hair tufts on oleander
Larvae of Syntomeida epilais on Nerium oleander. Photo: pending.
Identification
The caterpillars are orange, with clumps of black hair growing from black bumps along the body, and they grow from 3 mm to 40 mm (about 1½ in) long (UF/IFAS); Clemson gives up to 2 inches and calls the mature caterpillar orange-red. The hairs do not sting, and UF/IFAS says handling the larvae is painless, unlike some other hairy caterpillars. The eggs are pale cream to light yellow spheres under 1 mm across, laid in clusters of 12 to 75 under the young leaves.
The adult is the polka-dot wasp moth. Its body and wings are an iridescent blue-green, with small white dots on the body, wings, legs and antennae and a red-orange tip to the abdomen. The wingspan is 45–51 mm (about 1¾–2 in), and the sexes look alike. It is called a wasp moth because it resembles a wasp, and unlike most moths it flies slowly by day. Its caterpillars store heart poisons (cardiac glycosides) from the oleander, and UF/IFAS says birds and small mammals do not eat them.
Easily confused with
- Spotted oleander caterpillarHarmlessLight orange with six rows of silver spots ringed in dark brown and tufts of reddish-brown hair, and it feeds alone rather than in a group. UF/IFAS says it is rarer, mostly in the Keys and south Florida, and needs no control.
- Saltmarsh caterpillarHarmlessIts body is densely covered in hair all over, where oleander caterpillars carry separate tufts of black hair on a bare orange body. UF/IFAS says it needs no control on oleander.
- Wasps (for the adult moth)Beneficial — leave itThe polka-dot wasp moth is dotted with small white spots on its body, wings, legs and antennae, has a red-orange abdomen tip, and flies slowly by day.
Damage symptoms
Early damage is easy to recognise (UF/IFAS). The young caterpillars feed in a group under the leaves and eat the tissue between the veins, so new shoot tips turn light brown and lacy, and the group is under those leaves or the ones just below. From the fourth instar the caterpillars eat whole leaves, and it is these larger ones that can defoliate a bush: in as little as a week (UF/IFAS Gardening Solutions), or a few days in a severe infestation (Clemson). Total defoliation does not kill oleander, but UF/IFAS says repeated defoliation year after year can leave it more open to other pests such as scale insects.
- Light-brown, skeletonised new shoot tips
- A group of small orange caterpillars under the browned leaves
- Pale cream to yellow egg clusters under young leaves
- Whole leaves eaten, then bare stems
- Clusters of pupae in a thin hairy web in bark crevices or under the eaves
- Blue-green, white-spotted moths flying slowly by day
Lifecycle & degree days
Female moths perch on oleander and call with ultrasound, which people cannot hear, and mating happens two or three hours before dawn (UF/IFAS). Eggs are laid in clusters under the leaves of young shoots. The young caterpillars feed as a group, then split up and eat whole leaves from the fourth instar. Grown sixth-instar caterpillars leave the plant and pupate together in a sheltered spot, often where walls meet the eaves. The species is native to the Caribbean region. It lives year-round in south Florida and the Keys, but cold winters usually kill it in north and north-central Florida, and it recolonises those areas each spring.
- Egg hatch
- 2–6 days, depending on temperature
- Instars
- 6
- Group feeding
- 2nd–3rd instars, about 8.5 days in summer
- Solitary feeding
- 4th–6th instars, about 19 days
- Pupation
- In groups, in bark crevices or under eaves
- Winter
- Year-round in south Florida; killed by cold further north
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Host crops
In gardens it feeds on oleander. UF/IFAS says the original host is thought to be a now fairly rare beach and pineland vine, Echites umbellata, and that the caterpillar moved onto oleander after the Spanish introduced it in the 17th century. Its range now follows oleander's, from northern South America and the Caribbean into Florida, southern Georgia and coastal areas of the southeastern states, but it is not found in California.
Monitoring & action thresholds
Action threshold
None numeric — act at the first brown tips
Extension sources give no numeric threshold. UF/IFAS says the insect is very easy to control while the young caterpillars are still feeding in groups, and that insecticides should be a last resort, because the damage is unsightly but does not kill oleander. EP574 adds Bt while caterpillars are small, and other approved insecticides when they are larger, only if necessary.
Through the warm months, check the new shoots for tips that have turned light brown, then turn over those leaves and the ones just below to find the group of caterpillars. Look for pale egg clusters under young leaves as well. Dark, limp caterpillars that turn to liquid have died of disease: UF/IFAS says to leave them on the bush, where the disease spreads through the rest. Check under the eaves and in bark crevices for pupal clusters, and remove them to cut down the next generation (UF/IFAS Gardening Solutions).
Beneficial
Biological control
Birds and small mammals will not eat these poisonous caterpillars, but insects do (UF/IFAS). Predatory stink bugs, including the spined soldier bug, suck out the larvae. Tachinid flies lay their eggs on large caterpillars, and the parasitic wasp Brachymeria incerta lays its eggs in the pupae. Red imported fire ants find the pupal clusters and eat them. Viral, fungal and bacterial diseases can kill huge numbers in some years. Bt kurstaki kills only caterpillars, and UF/IFAS says it has no toxicity to beneficial insects.
Tachinidae
Tachinid flies- Kind
- Wild — attract it
- Best for
- Wild — lays eggs on large caterpillars
Podisus maculiventris
Spined soldier bug- Rate
- 1–5 /m² per release, every 1–2 weeks (Sound Horticulture)
- Temp
- Lab: nymphs took 23 days at 77 °F (25 °C), 99 days at 59 °F (15 °C); none developed at 50 °F (10 °C)
- Best for
- Wild — conserve; no oleander release rate
Cultural controls
UF/IFAS calls pruning out infested shoots the most environmentally friendly control, and it is easy on bushes under about 6½ ft (2 m). It has none of the side effects of a spray. Oleander is poisonous, so wear gloves and wash your hands afterwards.
- Snip off browned shoot tips with the group of caterpillars on them
- Bag the cuttings and freeze them for 24 hours to kill the caterpillars
- Hand-pick large caterpillars into a bag to freeze, or drop them into soapy water
- Leave dark, limp, diseased caterpillars on the bush
- Remove pupal clusters from under eaves and bark crevices
- Never burn oleander prunings: the smoke carries the plant's toxins
Chemical, last resort
Insecticides are a last resort (UF/IFAS): the damage is unsightly but does not kill oleander, and pruning out the young groups kills no natural enemiesCheck any product before it goes on. Open the compatibility matrix →
- Bt kurstakiREI 4 h
Rating: the effect on this pest's natural enemies if a spray hits them or they feed on treated plants. REI is the re-entry interval on farm and greenhouse labels; home labels usually give none, so follow the label.
Sources
UF/IFAS EDIS EENY-009 (IN135): Oleander Caterpillar (H.J. McAuslane, 1997)
UF/IFAS EDIS EENY-017 (IN143): Spotted Oleander Caterpillar (H.J. McAuslane, 1997, rev. 2011)
UF/IFAS EDIS EP574: Key Plant, Key Pest: Oleander (Popenoe et al., 2019)
UF/IFAS Gardening Solutions: Oleander (accessed Sept 2026)
Clemson HGIC 1079: Oleander (revised 2019)
DiPel DF / Magic Gardener Caterpillar Killer DF label, EPA Reg. 73049-39 (2026)
Page status
Drafted from the sources below, then checked claim by claim against those sources on 24 September 2026.
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