Brood XXIII of the periodical cicada will emerge along the Mississippi River Valley starting in mid-May 2015. This 13-year brood occurs primarily in the western counties of the state. It would be wise to delay transplanting trees or woody ornamentals into the landscape until after the cicadas disappear, probably by late June or early July. Spray programs in nurseries and orchards may have to be adjusted to manage them.
Figure 1. Brood XXIII emergence map – due in 2015.
Cicada Damage
The damage from these insects will result from the egg laying activities of females. They slit the bark on pencil-sized twigs and lay their eggs in the wounds (Figure 2). This damage can easily destroy the current year’s growth and additional pruning is needed to get rid of the damaged area.
Figure 2. Egg-laying wound from periodical cicada. (Photo: Lee Townsend, UK)
Damage is usually worse on newly-set or young trees. Females begin to lay eggs a week or so after emergence. Plants can be protected in three ways: covering, spraying, and pruning.
Management Options
- Small trees can be covered with protective netting cheesecloth. Be sure to secure the bottom around the trunk. This covering will have to stay on for the next 4 to 6 weeks, or until egg laying is complete.
- Trees can also be sprayed. Orchards under a routine spray schedule should be sprayed roughly twice a week during the cicadas’ peak activity period. Spray requirements will vary according to intensity of the outbreak, which ranges from a few cicadas in some areas to massive numbers of the insect in other areas.
- A third alternative is to prune out egg-laying wounds before eggs hatch, especially in fruit orchards where juveniles feeding on roots may decrease fruit production. Although this is a time-consuming process, it may be a viable alternative considering the production life and long-term value of fruit trees.
By Lee Townsend, Extension Entomologist
Kentucky Pest News 