Tobacco budworm feeds on buds and petals of geranium, calibrachoa and petunia. Tobacco budworms are generally a pest of home gardens and landscapes. However, adult moths can enter greenhouses with rollup sides, and lay their eggs on geranium or petunia buds. Caterpillars feed on flower buds, so that flowers fail to open. Petals may also be chewed. Fecal droppings may also be evident.
Microbial insecticides such as Bacillus thuringiensis (B. t.) may be used against young, early instars, provided you can obtain good coverage. On plants such as geraniums where the caterpillars drill into the buds, B.t. may not be as effective. Against the older instar caterpillars, (in photo) spinosad or spinosad combined with a pyrethroid may be an option.