In the spring of their 13th or 17th year, mature periodical cicadanymphsemerge between late April and early June in fantastic numbers. Following the developmental phase, the adult cicadas are active for around 4 to 6 weeks total. Intrigued by all things nature and the cicada phenomena we created the perfect periodical duo. Grab a hat or shirt and tell your buddies you minored in the study of Cicadoidea.