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Past Articles Library | Organic Pest Control | Control Tobacco Budworm


(Helicoverpa virescens)

Tobacco budworm, also known as geranium or petunia budworm, feeds on the buds and petals of many commonly grown flowers, including geranium, petunia and nicotiana.



The adult stage is a moth with a wingspan of about 1 1/2 inches (3.75 cm). The wings are light green with brown overtones and a few wavy, cream-colored bands. The larvae have striping but can be quite variable in overall color. Dark forms are common but red, light green or light brown larvae also occur. Color differences are related, in part, to the color of the flowers on which the insects are feeding.



In the early evening, females lay single eggs on buds or leaves. The caterpillars become full-grown in about a month, drop to the soil and pupate. Adults emerge to repeat the cycle, with two generations normally produced each year. At the end of the season, when day length and temperatures begin to drop, the insects go into a state of suspended development (diapause), that they maintain through winter. Overwintering pupae generally are killed if exposed to temperatures below 20° F (-6.7° C), but warm soil microclimates, like those around the foundations of heated buildings, can allow many to survive for the following year.




The tobacco budworm is a serious pest of many garden flowers; the geranium being a particularly common host, leading to the name geranium budworm. Petunia and nicotiana are other common hosts, while rose and many other flowers such as snapdragons, penstemon, and angelonia, are occasionally damaged.




Caterpillars of the tobacco budworm usually attack the flower buds and ovaries of developing flowers. The damaged buds will fail to open, and this is often the first injury observed. Petals of emerged flowers are also chewed, giving the flowers a ragged appearance. The amount of damage the insects cause progresses through the growing season, becoming most noticeable in late summer. The small green worms are often hard to see, but you can easily see the droppings, which often are described as small black seeds. Damage by this insect is so severe that in some parts of the country people have stopped planting geraniums and petunias.




1. Monitor for budworm to detect early stages of an infestation. Check buds and flowers for small holes or black droppings.

2. In small plantings, the most practical control is hand picking the caterpillars. Tobacco budworm larvae are most active during dusk and evening hours and are best discovered at this time. During daylight hours, they often hide around the base of the plant.

3. Tobacco budworms, unfortunately, are difficult pests to control with insecticides because they are quite resistant, but if used when the worms are small, using Bacillus thuringiensis (also called Bt) which is in a product called Green Step Caterpillar Control is very good. (See Green Step Caterpillar information below).

Be careful how you use Bt products though because they can affect good caterpillars like butterflies.

4. Buy plants that are currently being bred to be more resistant to this pest.

5. Maintaining potted plants in protected areas, such as garages, between seasons can allow tobacco budworm pupae to survive in the soil. If potted geraniums or other tender perennial host plants are kept between seasons, remove all the soil to eliminate pupae and repot the plants before overwintering.

6. Control Tobacco Budworm by rototilling your planting areas. Working the soil in the fall is preferable, but spring tilling may also help crush some of the budworm pupa.


Use Green Step Caterpillar Control

What's great about Green Step is that is is a liquid concentrate.

This is a huge advantage because many Bacillus thuringiensis (Bt) products are a powder, but this spray allows you to thoroughly cover the entire plant.

Why Is Liquid Better

Liquid is better because Tobacco Budworms must eat the Bt in order for it to be effective.

On plants such as geranium, and petunias where the caterpillars drill into the buds and eat little of the outside surface, regular powder Bt is not effective, but liquid can better cover the surface area which vastly raises the likelihood of the caterpillars eating it.

Best results are obtained when treatments are made when the worms are small and during the evening hours when they are actively feeding and will eat the treated, exposed foliage.

Green Step Caterpillar Control kills:

1. Tobacco budworm, also called Petunia or Geranium Budworm

2. Worms and caterpillars on fruits, vegetables, ornamentals and shade trees

But it has no effect on:

1. Birds

2. Earthworms

3. Beneficial insects, such as honeybees and ladybugs

This product can be used on edible plants up to the day of harvest.

More Green Step Caterpillar Control Information

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