Cicadas emerging in Virginia after 17 years in hiding
UPDATE: Cicadas have been spotted emerging in several counties where ground temperatures have warmed above 64°, including Henry and Franklin counties.
Have you spotted any where you are?
After 17 years, the periodical cicadas known as Brood IX will be emerging from the ground throughout much of southwestern Virginia.
This generation of cicadas has spent all this time feeding on the nutrients from wooded plants in the soil, and now its time has come to mate and bring on the next one.
Three species of 17-year cicadas collectively make up Brood IX:
. Adults from this brood are expected to emerge in unison when soil temperatures exceed 64 degrees.
The cacophony of sounds, produced by the adult males, will continue for about four to six weeks after they first start emerging.
Organs on the abdomen of the male cicada, called "tymbals," rapidly vibrate to produce the familiar sound used to attract females for mating. Once the females have successfully mated, they will cut small slits in the twigs of trees and shrubs to lay their eggs.
When those eggs hatch, the immature cicadas, called "nymphs," will burrow into the soil where they will remain for another 17 years to start the process again.
Brood IX is one of many periodical cicadas found only in eastern North America that can have either 13- or 17-year life cycles. Periodical cicadas that are typically in the same stage of development, and that emerge together in a given region during the same year, are considered a single brood. Each brood is given a unique Roman numeral.
Interestingly, periodical cicadas are so in sync that they are nearly absent as adults in the years between mass emergences. According to Dr. Daniel L. Frank, the Director of Pesticide Programs at Virginia Tech, the reason so many appear at once likely has to do with survival in numbers. The more that emerge, the higher the chances of successfully reproducing to continue the next generation.
Cicadas are not considered major pests from a health standpoint. They are harmless and pose no threat to people or pets. As for your plants, the only noticeable injury they cause is a result of egg-laying by females. Because of the minor cuts cicadas make to small branches and twigs, the twigs may die and fall down or break. This type of damage, called “flagging,” may be fairly prevalent in our area once the cicadas begin emerging.
Be aware that mature trees likely will be fine from this stress. However, this damage may interfere with the growth of young trees and could even kill them. It may be best to postpone planting new trees until after the emergence. Dr. Frank suggests putting mesh netting over the young trees during the egg-laying period. He also suggests
using insecticide to control their populations, except in commercial tree plantings.
Though some may find them creepy or a bit of a nuisance, cicadas are actually very beneficial to the environment. Their emergence aerates the soil and their bodies provide nitrogen and other nutrients to the soil when they die. In addition, they serve as an excellent food source to various birds, mammals and fish.