Size Variation

Size varies tremendously among and within orders, families, and species of insects. The smallest extant insects known are about 0.2 mm in length and can be found among beetles of the family Ptiliidae and wasps of the family Mymaridae, which are egg parasitoids. Insects of this minute size are smaller than the largest one-celled protozoans. The largest extant insects are phasmid (walkingstick) species (up to 30 cm long), sphingid moths (wingspan of up to 30 cm), and some beetles of the genera Megasoma, Dynastes, or Goliathus (up to 100 gr). The high number of possible runners-up for the title "largest insect on earth" highlights another difficulty when dealing with size: What measure should be used?

Although insects are not as large as some other organisms, the range in size among insects is almost as large. For example, the difference in volume between the largest mammal (the blue whale) and the smallest (a minute shrew) is about 1:2 X 108. This is comparable to 1:1.5 X 108 for the two extremes among insects (ptiliid beetle and Goliath beetle).

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