Kentucky Cicada Watch 2008



Welcome to Kentucky Cicada Watch 2008

Brood XIV

shells

Last looks at Brood XIV... Accumulations of nymphal exuvia (shells) following the emegence of adults in Morgan county courtesy of D. Pedrick. A cleaned up accumulation there on June 2 was 36 inches in diameter and 20 inches high. Singing reportedly stopped on June 21.

The quiet may seem unusual but welcome as Brood XIV adults fade away. One part of their legacy will become more visible as twigs and branches begin to flag, the result of breaking due to egg-laying wounds made recently by females. Eggs hatch 6 to 10 weeks after they are deposited so clipping and removing flagged twigs (and the inserted eggs) may give some reduction in the numbers of nymphs that fall to the ground under individual trees and enter the soil to feed on tree roots. This may be useful for small trees with moderate or greater flagging that are still becoming established in the landscape. Cicada nymphs will be too small for the first few years to have an impact but by about the 6th year (2014) could be removing enough sap to reduce tree vigor. Research had not shown a benefit to treating the soil under trees to kill nymphs as they fall to the ground and enter the soil. The annual or "dog day" cicadas are still to come but will be barely noticeable compared to what many have experienced during the past few weeks where the periodical cicada has been very abundant.

cicada eggs
cicada eggs

This is what all the ruckus is about... Freshly laid periodical cicada eggs in a twig. Females may lay as many as 600 eggs in groups of about 20. The eggs hatch about 6 to 8 weeks after they are laid and the small nymphs drop from the trees and burrow into the soil. They will find rootlets and begin to feed on sap.

   

Cicada map

Emergence has occurred over most of the eastern two-thirds of Kentucky as of May 30. While all of a county with reported cicada activity is colored blue, it often is limited to specific areas in and around woodlots and forests.


Management recommendations for periodical cicadas in fruit This Kentucky Pest News article covers use of insecticides to prevent damage to fruit trees, small fruits and grapes.

Protecting Landscape Trees and Woody Shrubs from Damage

Periodical cicadas are potential pests of many trees and woody ornamentals, with the exception pines and other species that produce gummy substances when damaged. These insects can cause problems in orchards, vineyards, nurseries, home and commercial landscapes. Physical injury or “flagging” occurs after females slit twigs to insert batches of eggs. Twigs break at these weak spots and are left to dangle, turn brown and die. This “pruning” is not a serious problem for large trees but can adversely affect the developing structure of small trees. A more subtle impact can occur several years later as growing nymphs remove sap from roots.

  • New orchard or landscape plantings should be delayed until after periodical cicada activity has ended for the season.
  • Young trees can be covered with netting or cheesecloth to protect the tender twigs. This should be done when the first male singing is heard. Secure the covering around the trunk to prevent cicadas from climbing up to the limbs. The netting should be removed at the end of June or when cicada activity stops.
  • If practical, cicada nymphs can be prevented from feeding on roots of young trees by pruning out twigs with egg slits. This needs to be done within a three weeks after egg laying has ended. Although a time consuming process, it may be a viable alternative considering the production life and long term value of backyard fruit trees. Feeding by large numbers of nymphs over several years can reduce the vigor of small trees.
  • Insecticide applications generally are of limited use in protecting trees from damage, especially where cicadas are very abundant. Repeated treatment will be needed to deal with new arrivals. Orchards under a routine spray schedule should be treated about twice a week during peak cicada activity. Spray requirements will vary according to intensity of the outbreak, which can range from a few cicadas in some areas to massive numbers in other areas.

Some cats and dogs are intrigued by cicadas and may eat enough of them to cause an upset stomach but cicadas are not toxic and cannot sting.

Periodical cicadas will fly to things that produce noise at some frequencies so they may appear to "attack" weedeaters and lawnmowers. Being somewhat ungainly in the air, these insects may crash into people or machinery but it is unintentional.


Here are a few significant dates from a study of the emergence of this brood in 1991 at Robinson Forest by Dr. Paul Kaliz, UK Forestry Dept.

  • Emergence began on May 4, about 10 days earlier than 2008.
  • Widespread emergence by May 10, 1991. Males begin to call and form groups that chorus as they attract females for mating. Adults will use their piercing sucking mouthparts to feed on plant sap.
  • The last nymph caught leaving the soil on May 31, 1991
  • The last adult heard calling on June 16

Keep us up to date by sending your observations, pictures, etc. of Kentucky cicada activity to: Lee.Townsend@uky.edu.

Species in Brood XIV

Kalis found the periodical cicada population is his study to be comprised of three species. Links will take you to information about them and examples of their songs. Magicada septendecim (85%), M. septendecula (13%), and M. cassini (5%).


Links

University of Michigan Museum of Zoology Periodical Cicada Page

Here is a regional map of emergence sightings.

Periodical cicadas in Kentucky (Entfact 446) This fact sheet list has information on the life cycle of cicadas and the broods of periodical cicadas that occur in Kentucky.

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This page is maintained by Lee Townsend, Department of Entomology, University of Kentucky. Please send questions or suggestions to: Lee.Townsend@uky.edu