Shrill insects, such as cicadas (7 letters), are known for their loud and high-pitched calls. These insects are found in many parts of the world and are typically associated with hot, humid climates. They are often seen in trees and shrubs, and their calls can be heard during the day or night. Cicadas are a type of insect that belongs to the order Hemiptera, and they are known for their long life cycles, which can range from two to 17 years.