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Hymenoptera

life science Maturity 5-7 Next article →

Hymenoptera is a massive order of insects. It includes familiar groups like bees, ants, and wasps, as well as sawflies.

AD2009Sep09 Vespula germanica 01
AD2009Sep09 Vespula germanica 01

Scientists have described over 150,000 living species. They have also identified more than 2,000 extinct species. The name comes from Ancient Greek words meaning "membrane" and "wing."

Xyelapusilla
Xyelapusilla

This refers to their characteristic membranous wings. These insects are vital to the planet. They act as essential pollinators for many plants. However, they also play roles as predators and parasites.

Most hymenopterans undergo holometabolism. This is a process of complete metamorphosis. The insect begins as a wormlike larva.

Large rose sawfly (Arge pagana stephensii)
Large rose sawfly (Arge pagana stephensii)

It then enters a pupal stage where it remains inactive. Finally, it emerges as a fully developed adult. This lifecycle allows the young and adults to live in different ways. For example, larvae often eat different foods than the adults. This reduces competition between the different life stages.

Anatomy varies greatly across the order. Most species have well-developed mandibles for chewing.

Bombus muscorum1
Bombus muscorum1

Many have also evolved a long proboscis to drink nectar. Their wings usually consist of two pairs. A special structure called hamuli locks the hind wing to the fore wing. This coupling keeps the wings held together during flight. They also possess large compound eyes and three small simple eyes called ocelli. These eyes help them navigate their environments.

Females possess a specialized organ called an ovipositor. This tool is used for laying eggs in specific locations. In ancestral species, the ovipositor is blade-like for slicing plant tissue. In many other species, it is modified for piercing. In some groups, the ovipositor has become a stinger.

AD2009Sep09 Vespula germanica 01
AD2009Sep09 Vespula germanica 01

In these cases, eggs are laid from the base of the structure. The tip is used only to inject venom. This venom can immobilize prey or serve in defense.

Scientists divide Hymenoptera into two main suborders. The first is Symphyta, which contains sawflies and horntails. These insects lack a narrow waist. Their larvae are often eruciform, meaning they look like caterpillars.

They usually have three pairs of true legs and several prolegs. The second suborder is Apocrita, which includes wasps, bees, and ants. These are defined by a narrow waist called a petiole.

AD2009Sep09 Vespula germanica 01
AD2009Sep09 Vespula germanica 01

Apocrita larvae typically lack legs, prolegs, and ocelli.

Evolutionary history shows that Hymenoptera is an ancient group. Molecular analysis suggests they are the earliest branching group of Holometabola. They originated during the Triassic period.

Xyelapusilla
Xyelapusilla

The oldest known fossils belong to the Xyelidae family. Social species, such as ants and bees, appeared later during the Cretaceous. Researchers like Alex Rasnitsyn and Michael S. Engel have studied this history. In 2023, a molecular study used ultra-conserved elements to confirm their family tree. This provided a robust phylogeny for the entire order.

Reproduction in this order is often unique due to haplodiploidy. This is a system where sex is determined by chromosome numbers. Fertilized eggs have two sets of chromosomes and become diploid females. Unfertilized eggs have only one set and become haploid males.

Bombus muscorum1
Bombus muscorum1

This allows the female to control the sex of her offspring. Some species even use thelytoky. This is a form of parthenogenesis where females create embryos without fertilization. This process helps maintain genetic diversity in certain colonies.

Many species are also parasitoids. These insects lay eggs in or on a host organism. Once the eggs hatch, the larvae consume the host. Some are even hyperparasitoids, which parasitize other parasitoids.

Specimen of Podalonia tydei (Le Guillou, 1841)
Specimen of Podalonia tydei (Le Guillou, 1841)

This complex web of life shows how interconnected these insects are. Because they are so important for pollination, habitat loss is a major threat. Losing these species could have huge ecological consequences for the world.

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🖼️ Images & Media (21)
File:European wasp white bg.jpg
European wasp white bg.jpg
File:Pseudacrossus przewalskyi (Reitter, 1887).jpg
Pseudacrossus przewalskyi (Reitter, 1887).jpg
File:Elenchus koebelei.jpg
Elenchus koebelei.jpg
File:Corydalus cornutus illustration (rotated).png
Corydalus cornutus illustration (rotated).png
File:Osmylus_(white_background).jpg
Osmylus_(white_background).jpg
File:Arctia villica SLU.JPG
Arctia villica SLU.JPG
File:RHYACOPHILA DORSALIS Male Pont Forge de Sailly Watigny 02 MHNT.jpg
RHYACOPHILA DORSALIS Male Pont Forge de...
File:Common house fly, Musca domestica.jpg
Common house fly, Musca domestica.jpg
File:Scorpionfly (white background).jpg
Scorpionfly (white background).jpg
File:Pulex irritans female ZSM (white background).jpg
Pulex irritans female ZSM (white background).jpg
File:Endelomyia rosae.jpg
Endelomyia rosae.jpg
File:Xyelapusilla.jpg
Xyelapusilla.jpg

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