Source: Curtis Young, OSU Extension
OK, let’s dispel any of the wild rumors right now!
Are periodical cicadas a threat to field crops? The quick and dirty answer to this question is NO! Are they a threat to the health and welfare of anything? There is no quick and dirty answer to this question.
The best way to answer the second question is to start by looking at what the periodical cicada is, what it feeds on, where one would expect to find them, and its life cycle.
The periodical cicada or 17-year cicada is an insect with an extremely long life cycle that takes 17 years to get from the egg stage to the adult stage. Some people mistakenly refer to this insect as a locust. Unfortunately, locusts and cicadas are not one-in-the-same. Locusts are a type of grasshopper (Order Orthoptera). Cicadas (Order Hemiptera) are not grasshoppers. And the 2 look nothing like one another.
The periodical cicada feed mostly in their nymphal stages and are hosted by trees of many species. And since it takes 17 years of feeding by the nymphs, the trees have to be old and well established, minimally 20+ years old.
Therefore, periodical cicadas are going to be found in and around long-standing woodlots, forests and landscapes (homes, parks, and cemeteries), especially those that have been established in or next to woodlots. What does this preclude? We will not find periodical cicadas in crop fields, pastures, landscapes recently established on field crop ground, housing developments where all of the ground was excavated, or basically anywhere where there isn’t long established trees. There are also northern limits to their natural range (e.g. they do not exist very far into the state of Michigan).