This spring, southern Indiana will see the emergence of Brood X of the 17-year cicadas. If you live in a wooded area (has been wooded the last 17 years) you will likely get first-hand experience in hearing their almost deafening song. Good news, though. Cicadas are not harmful to humans, they provide food for some wildlife species, and generally cause only cosmetic damage to trees. There are some trees, however, that may need protection.

We will likely see major emergence times from mid-April and continue through mid-May. However, this may shift slightly depending on if we experience warmer or cooler spring temperatures.

The 17-year cicadas will look different than our annual cicadas. They are really quite colorful. Their bodies are nearly black colored, with red eyes, and amber veins and highlights in their wings.

The 17-year cicadas will feed on more than 270 species of woody plants with a slight preference to deciduous trees. Cicadas cause injury to trees when they lay their eggs into the tree bark. They prefer laying their eggs in branches that are three-sixteenths to one-half inch in diameter. If enough cicadas lay their eggs on a small twig or branch it can kill it. The damage I have seen in the past, especially with large trees, is that the branch tips may die back and fall off the tree. Again, this damage is mostly cosmetic.

It can get damaging for smaller trees that may only be three to four years old or young shrubs. If you have young trees or shrubs the best way to protect them is to cover them with a mesh fabric while the cicadas are active. Drape the fabric over branches smaller than three-eighths of an inch and secure the fabric at the base to prevent cicadas from crawling under it.

For fruit growers and nurseries, the recommendation is also to use mesh fabric. Mesh fabric can reduce cicada injury by over 95%, whereas insecticides only reduce injury by about 75%. Also, many of the insecticides that work best on cicadas also can harm beneficial insects and can cause spider mite infestations later in the season. If netting is not feasible due to it being a large planting, pyrethroid insecticides will need applied repeatedly during the active time of the cicadas. Make sure to read and follow all labeled directions prior to spraying insecticides.

Personally, I enjoy listening to the cicadas while sitting outside enjoying warmer temperatures next to a campfire. They can also be quite a topic for conversation with their colorful appearance, loud songs, and interesting 17-year life cycle.

To view images and find additional information you can visit https://www. or contact the Purdue Extension-Knox County office by calling 812-882-3509 or by emailing

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