Insect Classification – Subclass Apterygota

Insects That Lack Wings
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Silverfish. – Getty Images/E+/arlindo71
Silverfish are apterygotes, meaning they are primitively wingless insects. Getty Images/E+/arlindo71

By Debbie Hadley
Insects Expert

Updated October 29, 2015.
The name Apterygota is Greek in origin, and means “without wings.” This subclass contains primitive hexapods that do not fly, and were wingless throughout their evolutionary history.


The primitively wingless hexapods undergo little or no metamorphosis. Instead, the larval forms are smaller versions of their adult parents. Apterygotes molt throughout their lives, not just during the growth phase. Some apterygotes, like silverfish, may molt dozens of times and live several years.

Three of the five orders classified as Apterygota are no longer considered true insects. Diplurans, proturans, and springtails are now referred to as the entognathous orders of hexapods. The term entognath (ento meaning inside, and gnath meaning jaw) refers to their internal mouthparts.

Orders in the Subclass Apterygota:

Diplura – diplurans (Entognatha)
Protura – proturans (Entognatha)
Collembola – springtails (Entognatha)
Thysanura – silverfish and firebrats (Insecta)
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Microcoryphia – jumping bristletails (Insecta)


“Apterygota,” by John R. Meyer, Department of Entomology, North Carolina State University. Accessed online October 29, 2015.
Hexapod taxonomy lecture slides, by Christopher Brown, Department of Biology, Tennessee Tech University. Accessed online October 29, 2015.
Borror and DeLong’s Introduction to the Study of Insects, 7th edition, by Charles A. Triplehorn and Norman F. Johnson.

Tiny black bugs, with wings, that gather around window sills! Help!

Asked March 23, 2015, 6:09 PM EDT


Around 5 months ago I had an infestation of tiny black bugs in my kitchen window. They did fly, although they mostly ran. Every morning I would find around 35 bugs in the kitchen window and floor, most of them dead. Sometimes I would see them flying in my bedroom or living room, but just a couple of them. I cleared my trash every day and they didn’t go. I even found some inside my fridge. A pest control company came, and bombed and sprayed my place. Their theory is that they were fleas (nor sure about it) After that, I still saw a couple of them and decided to throw away some organic soil I had for my plants. After that, they were gone, but also the winter came.

A few weeks ago I think I saw a similar little black bug flying a couple of times, once in my bedroom, once in my living room. But then nothing happened, so I thought those were probably different.

Yesterday I saw one of the bugs AGAIN in the kitchen window sill. It is a bit larger than the ones I saw before, but I think it is the same bug. It was dead. This morning I was another two! One is minuscule, the other one a but bigger, but smaller than the one I saw first. I left my kitchen window open for 2 days for the first time in months, as the winter here (Cambridge, MA) is extremely cold. I’m very concerned cause I don’t know if maybe there is a nest outside my window (how did they survive the winter?!) or if there is something hidden in my place. I don’t think they are fleas, as they do fly, and I don’t have any animals, nor bites. Please help me! I’m attaching a picture of the bigger one I found this time.

Other insects, such as the flea and louse, are wingless and can only crawl or jump to move around. Crawling insects here refers to insects that are perceived as pests mainly due to their crawling behaviour.

Insect characteristics
Insects are distinguished by having an exoskeleton with a three-part body, consisting of: a head with compound eyes, a pair of antennae and very variable mouthparts; a thorax with six legs and often one or two pairs of wings; and an abdomen.

Most insects go through a life cycle starting with eggs and a series of developmental stages or moults, before they reach their adult stage. This is typically egg, larva (eg caterpillar, maggot), pupa (often sealed in a cocoon) and adult, which often has wings.

Other arthropods, the arachnids (spiders, ticks, mites, scorpions) and the Myriapods (centipedes) are all wingless so only move around by crawling. They are characterised by having two body sections, the cephalothorax (fused head and thorax) and abdomen with eight legs. Ticks and mites have a similar life cycle to insects, with egg, larva, nymph and adult stages. Spiders and scorpions produce eggs and progress through larval stages in the egg, hatching as small immature adults that have to go through several moults to grow to the adult size. These are included with the crawling insects for convenience.

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