seal  Purdue News


May 12, 2004

A list of Purdue University and Indiana University experts who can talk about the effects of periodical cicadas is available online.

Facts about brood X (ten) periodical cicadas

WEST LAFAYETTE, Ind. - Cicadas are beginning to emerge southern Indiana where the outer shell they shed as they become adults has been seen. Here are some things you might want to know about the insects:

• Periodical cicadas emerge every 13 years or every 17 years.

• There are three species of 17-year and four species of 13-year cicadas. Annual cicadas are quite distinct from periodical cicadas.

• Brood X includes all three of the 17-year species.

• Cicadas don't bite, don't sting, don't carry disease, and are not poisonous.

• Cicada groups received their brood names from a Department of Agriculture employee, Charles Marlatt. He called the group that emerged in 1893 Brood I; 1894's group was Brood II, etc.

• Cicadas are not grasshoppers. Cicadas are not locusts. Locusts are grasshoppers and vice versa.

• Only male cicadas sing and each species has its own songs for mating and to signal danger.

• Cicadas sing from about dawn until just after dusk, but mostly in the afternoon.

• Females respond to males by flicking their wings to make clicking sounds.

• Brood X cicadas are expected to emerge in mid- to late May. Cicadas emerge when the soil temperature reaches approximately 64 degrees Fahrenheit.

• The emerging insect is in the final nymph stage.

• The nymph climbs a vertical object, where it sheds its outer layer and becomes a winged adult.

• Adults will be present approximately three to four weeks while they mate and lay eggs.

• Females use sharp appendages at the ends of their abdomens to make small slits in tree twigs where they lay their eggs.

• Female periodical cicadas lay 400-600 eggs.

• When they lay eggs, cicadas damage tree twigs with diameters between 3/16" and 7/16".

• Females are most likely to lay eggs on oak, hickory, maple, flowering fruit trees, mountain ash and grape, although they reportedly have used as many as 200 different species.

• Eggs hatch in about six weeks.

• The tiny nymphs drop to the ground where they burrow 8-12 inches into the ground.

• For 17 years, the nymphs grow by sucking on fluid from deciduous tree roots.

• Birds and rodents eat cicadas.

• Your pets won't be harmed by eating cicadas. However, if your pet eats too many of the insects, it may become ill.

• Cicadas may benefit ecology because of the natural pruning that occurs when twigs drop off after the cicada eggs are gone. This results in increased fruit yields in following years.

• When cicadas emerge, they aerate the soil, and their decaying bodies add a lot of growth-stimulating nitrogen to the soil.


Writers: Susan Steeves, (765) 496-7481,

David Bricker, (812) 856-9035,

Ag Communications: (765) 494-8396; Beth Forbes, (765)
Agriculture News Page

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