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Entomology (Study of Bugs)/Terminology used describing insects


I have been troubled with the terms: heterometabolic and hemimetabolic insects.
Are both terms the same or not? Because I get conflicting answers.
It seems that that hemimetabolic insects are (in aquatic entomolgy) the onces that live in 2 environments while paurometabolism live in the same.
But describing land insects then they dont make distinction and hemimetabole means just incomplete change.
But then when searching some more I noticed that other websites state that heterometabolic insects are (in general, both aquatic and rural) insects with an incomplete change and that they are divided in hemimetabolic and paurometabolic.
So I am getting confused.
And to make it even worse, I found (ie) other websites that say it the other way ( where they state that it is the hemimetabole insects that are divided in the heterometabole and paurometabolic...
So what is the correct use of this terminology?


Dear Gil - I can appreciate your confusion, as I believe that the explanations on the web site you found are unnecessarily complex. I'll refer you instead to where you will find a simpler explanation that I find more in line with what I was taught more than 50 years ago. The principal difference between hemimetabolous insects (incomplete metamorphosis) and paurometabolous insects (gradual metamorphosis) is that the immatures and adults of the former have different habitats and a very different physical appearance whereas the immatures and adults of the latter are similar both in habitat and physical appearance. I believe that the term incomplete metamorphosis helps define those insects whose immature and adult forms are very different, but that they lack an intermediate 'resting' pupal stage characteristic of complete metamorphosis. Gradual metamorphosis I feel is self-explanatory, as the changes in the insects' appearance as it moves through the immature stages to adult are indeed gradual, unlike the abrupt transition seen in both incomplete and complete metamorphosis.

Hope this helps,

Entomology (Study of Bugs)

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Ed Saugstad


Will accept most questions in general entomology, including those related to medical entomology, taxonomy, ecology, arthropod surveillance, and pest management. If you are requesting a 'mystery bug' identification, PLEASE either attach an image to your question, or post an image on a web page (such as Flickr) so that I can look at it, as verbal descriptions frequently are insufficient for a definitive identification.


21 years in the U.S. Army as a medical entomologist; duties varied from surveillance of pest populations (including mosquitoes, cockroaches, ticks, and stored products pests) to conducting research on mosquito-virus ecological relationships and mosquito faunal studies. Ten years as a civilian analyst for the Department of Defense, primarily on distribution of vector-borne diseases worldwide. Limited experience on surveillance of agricultural insects in North Dakota and Indiana.

Entomological Society of America, West Virginia Entomological Society, Society for Vector Ecology, National Speleological Society, West Virginia Association for Cave Studies.

American Journal of Public Health, Contributions of the American Entomological Institute, Japanese Journal of Sanitary Zoology, Journal of Economic Entomology, Mosquito News, and Mosquito Systematics.

B.S. in entomology from North Dakota State University in 1963, M.S. in entomology from Purdue University in 1967.

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