16 Facts About Cicadas

Brood X (Cicadas) are now beginning to emerge. Below are sixteen facts about this insect that is helpful to know:

  1. Periodical Cicadas and Annual Cicadas are different species. Periodical ones (like Brood X) emerge every 13- or 17-years when soil temperatures reach 64 degrees. They will be all over the place in Northern Virginia until around the end of June. Annual cicadas will still start to appear later in the summer.
  2. Before becoming adults, immature cicadas will climb up plant material to find a place to safely molt. This does no damage to the plant as periodical cicadas do not have chewing mouth-parts.
  3. Periodical cicadas rarely eat, if at all. In fact, the male cicada does not have a fully developed digestive system. Females very seldom take in nutrients to aid in flight and reproduction.
  4. Cicadas are very poor fliers. Their wings are much denser than other species due to high percentages of chitin (the same material lobster shells and fish scales are made of).
  5. Customers may see damage to their lawns from foraging animals like skunks, raccoons, or birds due to high populations emerging at the same time. Snakes won’t damage the yard, but also will eat cicadas as they emerge. Depending on severity, this should be sodded in the Spring, or reseeded in the Fall.
  6. Contrary to popular belief, cicadas are not locusts. The common misconception comes from historical references in the bible of locust infestations. Locusts, like the grasshopper have chewing mouthparts which cicadas lack.
  7. Cicadas are not toxic; however, if a pet were to eat a large amount the owner could expect some digestive disturbances.
  8. The female cuts open thin limbs of trees (less than 0.5” in diameter) using her ovipositor and excretes a hormone that works as a plant growth regulator to keep the wound open. This provides an incubation site for the eggs she lays.
  9. The damage symptoms from egg laying will manifest as some minor dieback of these smaller branches. Damaged limbs can be pruned out, the tree will flush out new growth. The sheer weight of the eggs and cicadas in smaller branches may also cause breaks if heavy wind or rain are in the area.
  10. Evergreen trees and shrubs are largely unaffected by periodical cicadas. Deciduous trees are more targeted as laying sites. In 2004, Paper-Bark Maples and Red Bud trees were hit harder than others.
  11. If customers have particularly valuable trees which may be more vulnerable as laying sites, they can cover the tree in netting to provide a mechanical barrier. Valuable trees with many smaller limbs such as Weeping Japanese Maples, will be an attractive host for cicada eggs. Even still, damage will be minor and the tree should make a full recovery.
  12. Younger trees will be the most susceptible, especially those with narrower trunks. This would likely be the only fatality from brood X cicadas, and even still, complete death of a tree is very unlikely.
  13. Cicadas naturally aerate as they emerge. Casts will be decomposed by other insects and micro-organisms in the soil. This will add organic content to the soil profile and is beneficial to the lawn. Cicadas do not feed on turfgrass roots.
  14. Spraying pesticides to control periodical cicadas is like trying to stop the waves of the ocean. Not only will insecticides barely dent the immense population expected, they will also kill out several beneficial insects. While their numbers will be high, customers need to tolerate this insect pest.
  15. Immature stages of the periodical cicadas are the ones which feed. They feed below ground on tree roots for 13- or 17-years. Damage is largely negligible.
  16. The congregational song cicadas sing from the trees is done to establish territorial boundaries as well as ward off predators. Researchers think that one of the reasons for the long time between emergences is to throw off predators to give the cicada the best chance of reproduction.
Eggs laid in wounds created by female periodical cicadas
Damage from egg laying
Cicada casts and nymphs grabbing onto foliage to molt