The tobacco budworm is a pest which affects field crops such as alfalfa, cotton, tobacco, soya, and others; however, it can also attack cucurbits, peppers, and tomatoes, especially when its favoured crops are in abundance. It is also a problem for some ornamental crops such as geraniums, birds of paradise, chrysanthemums, gardenias, petunias, and others. Although the use of sex pheromones is helpful for attracting moths, it is not a pest control tool to rely upon completely, since it is not very efficient. The tobacco budworm is very similar to Helicoverpa zea in terms of its habits, with differences found between the patterns of colour on the adults. The larger larvae share many similarities; only a detailed look will reveal the differences between them. A key difference with the corn earworm is that Heliothis virescens has not been found on corn or sorghum.
Lifecycle and appearance of the tobacco budworm
The eggs are laid in the flower buds, the fruit, and the growth areas; they have a spherical shape with a flat base and develop a whitish-yellow and grey colour as they age and hatch after two to three days. During this phase, it is difficult to differentiate these eggs from those of the corn earworm. The larvae pass through five to seven instars over 17 to 22 days. They have a yellowish-green colour and a yellowish-brown head during the first stages, and a greenish colour with side and back stripes and a brown head during the later instars. There are instances where the colour varies so much that larvae with a pale green, pink, or dark red colour have been found. Pupation takes place on the ground, lasting around 22 days. During this phase, the insect’s colour is a bright reddish-brown, turning dark brown shortly before the adult hatches. The adults have a brown colour with shades of green and three horizontal black stripes on the forewings, whilst the hindwings have a whitish colour with black edging along the sides. Their lifespan ranges from 15 to 25 days, depending on the temperature.
The larvae make holes in shoots and flower buds, although sometimes they can be found on the growing tips, the leaf petioles, and the stems. In the absence of reproductive tissue, the larvae easily feed on leaf material. When the caterpillars move towards and penetrate the fruit, the risk of disease infection increases considerably.