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How to identify it
- Caterpillars vary in color, from green, tan or brown to pink, red, maroon or nearly black, often matching the flowers they eat.[1][4][3][5]
- Older caterpillars usually have a brown head and light and dark stripes along the body. Tiny black microspines give the skin a rough texture.[4][5][3]
- Full-grown caterpillars reach about 1.4 to 1.5 inches.[4][3]
- Moths are pale or light green with gray or brown tones and a few wavy cream bands, spanning about 1 to 1 1/2 inches.[1][4][5]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Corn earworm | A related caterpillar that looks nearly identical to tobacco budworm and feeds on many of the same crops. The larvae are hard to tell apart without magnification, and young ones cannot be separated at all; adults usually differ in wing color.[1][4] |
Where it lives
A major pest of cotton and tobacco nationwide, especially in the southern United States. In Colorado problems center on the Denver metro area and Grand Junction. It does not survive Minnesota winters and arrives there on air currents in late summer, and Iowa State is unsure whether it survives Iowa winters or blows in each year.[1][3][2]
Biology and life cycle
Moths are active in the early evening and lay eggs on buds or leaves.[1][5]
Caterpillars mature in about a month, then drop to the ground and pupate in the soil. Colorado State gives two generations a year, Washington State two or more, Iowa State at least two per summer, and NC State typically four in North Carolina.[1][5][3][4]
It winters as a pupa 2 to 6 inches deep in a packed earthen cell. Survival is best in warm spots such as soil next to heated buildings, so damage is worse after mild winters.[1][3]
Pupae can also survive in the soil of potted plants brought indoors, and the insect can stay active year-round in greenhouses.[1][3]
It can develop on more than 100 plant species. Iowa State lists geranium as its favorite flower, along with impatiens, petunia, nicotiana, ageratum and marigold; Washington State adds rose.[6][3][5]
Damage and signs
- Caterpillars tunnel into flower buds and chew petals, leaving small holes. Damaged buds fail to open, and flowers that do open look ragged.[1][5]
- On petunia, caterpillars also feed on the petals of open flowers. If buds run out they move to shoot tips and leaves.[5]
- Most caterpillars hide at the base of plants by day and climb up to feed at dusk.[1][5]
Health risk
It feeds on plants; these extension sources list no risk to people.[1][2][3]
Control
Prevention
Ivy-leaved geraniums are damaged far less than zonal types. If you keep potted geraniums over winter, remove the old soil and repot to get rid of pupae.[1][5]
Traps and physical control
Hand-pick caterpillars and damaged buds. Search with a flashlight at dusk, when the caterpillars climb onto plants.[1][5][2]
Pesticides
Spray late in the day: much of the feeding happens inside buds and at night. Spinosad works best applied after dusk, once bees have stopped foraging; it is toxic to bees, so never spray flowers bees are visiting.[1][5]
Pyrethrins, insecticidal soap and imidacloprid will not control it, according to Colorado State.[1]
Where sources disagree
Bt: Colorado State says Bt can work on petunia, where caterpillars feed on the outside of flowers, but is likely to fail on geranium; Washington State calls it somewhat effective on young caterpillars feeding on plant surfaces; Minnesota and Iowa State say it does not work well against this insect.[1][5][2][3]
Pyrethroids: Colorado State lists certain pyrethroids as effective but warns they are hazardous to bees, and Minnesota lists residual pyrethroids, while Iowa State says sprays are likely to fail because of widespread resistance, especially to pyrethroids. A 2022 review lists tobacco budworm among the heliothine moths that have developed resistance to many insecticide classes.[1][2][3][7]
Winter cold: Colorado State says overwintering pupae are generally killed below 20 degrees F, while Iowa State gives -20 degrees F.[1][3]
Moth activity: Colorado State says moths are active in the early evening, while NC State says they are active during the day in tobacco fields.[1][4]
More from NC State Extension
Caterpillars take on the color of what they eat, from green to pink, red or maroon, but always carry tiny black spines that give the skin a rough texture; the species overwinters as pupae in the soil.[4]
Common questions
- What's eating holes in my geranium buds?
- Tobacco budworm caterpillars, also called geranium budworms, bore into the buds.[1]
- Why can't I find the caterpillars during the day?
- Most hide at the base of the plants by day and climb up at dusk.[1]
- Why didn't Bt or my usual spray work?
- Caterpillars inside buds eat little of the sprayed surface, and many populations resist common insecticides, especially pyrethroids. Hand-picking at dusk is often the most practical control in small gardens.[2][3][1]
Sources
- Colorado State University Extension, “Tobacco (Geranium) Budworm (Fact Sheet 5.581).” extension.colostate.edu/resource/tobacco-geranium-budworm/ (accessed 2026-11-11)
- University of Minnesota Extension, “Tobacco budworms.” extension.umn.edu/yard-and-garden-insects/tobacco-budworms (accessed 2026-11-11)
- Iowa State University Extension and Outreach, “Tobacco Budworm (Yard and Garden).” yardandgarden.extension.iastate.edu/encyclopedia/tobacco-budworm (accessed 2026-11-11)
- NC State Extension, “Tobacco Budworms.” content.ces.ncsu.edu/tobacco-budworms (accessed 2026-11-11)
- Washington State University Extension, “Petunia: Tobacco budworm (Hortsense).” hortsense.cahnrs.wsu.edu/fact-sheet/petunia-tobacco-budworm/ (accessed 2026-11-11)
- Environmental Entomology, via PubMed, “Blanco, Teran-Vargas, Abel, Portilla, Rojas, Morales-Ramos and Snodgrass (2008), Plant host effect on the development of Heliothis virescens F. (Lepidoptera: Noctuidae).” pubmed.ncbi.nlm.nih.gov/19161698/ (accessed 2026-11-11)
- Annual Review of Entomology, via PubMed, “Walsh, Heckel, Wu, Downes, Gordon and Oakeshott (2022), Determinants of insecticide resistance evolution: comparative analysis among heliothines.” pubmed.ncbi.nlm.nih.gov/34995087/ (accessed 2026-11-11)
- iNaturalist, “Chloridea virescens taxon page (order and family).” www.inaturalist.org/taxa/509353 (accessed 2026-10-06)