Hymenoptera

Most wasps live less than one year, some workers for just a few months. Queens sometimes live for several years.

Hymenoptera is one of the four large insect orders exceeding 100,000 species in the world, the other major orders being Coleoptera, Lepidoptera and Diptera (Gauld and Bolton 1988, Goulet and Huber 1993). The Hymenoptera order contains about 115,000 described species and authors estimated that there are between 300,000 and 3,000,000 species of Hymenoptera (Gaston 1991), possibly around 1,000,000 (Sharkey 2007). These estimates mean that only 1/10 has been described so far and 9/10 awaits description. However, the number of Hymenoptera species is difficult to estimate with accuracy, as most of the mega diverse regions of the world have not been extensively studied and inventoried regarding this group (LaSalle and Gauld 1993).

Hymenoptera have been traditionally subdivided into three assemblages (the paraphyletic sub-order Symphyta and the monophyletic Aculeata and Parasitica belonging to the sub-order Apocrita). Each group exhibits different biology. ‘Symphyta’ are mostly phytophagous and are the most primitive members of the order. Parasitica are mainly parasitic species but some of them have returned secondarily to phytophagy, while Aculeata encompass a larger spectrum (predators, pollinators, parasitoids); all eusocial hymenoptera belong to this last group.

Members of the Hymenoptera are familiar to a general audience and common names exist for a large variety of groups: “wasps”, “bees”, “ants”, “bumblebees”, “sawflies”, “parasitic wasps”. Hymenoptera adult sizes range from the very small Mymaridae (0.5 mm) to the large aculeate wasps (up to 5 cm long in Europe). This group of mandibulate insects is well defined by the combination of several characters: they have two pairs of functional wings (with the exception of apterous species) bearing fewer veins than most other insect groups and rarely more than seven cross veins. The abdominal tergum 1 is fused to the metanotum and in most Hymenoptera the metasoma (apparent gaster) is joined to the mesosoma (apparent thorax) by a petiole.

Ecologically and economically few groups of insects are as important to mankind as the Hymenoptera. Bees provide the vital ecosystem service of pollination in both natural and managed systems (Gallai et al. 2009) while parasitic Hymenoptera control populations of phytophagous insects (Tscharntke et al. 2007) and can be effective agents for control of pest insects (Bale et al. 2008, Brodeur and Boivin 2004, Jonsson et al. 2008). Some of the phytophagous hymenoptera have an intimate association with their hostplants (Nyman et al. 2006) and can also be considered as major pests to forests (e.g. Diprionidae) (De Somviele et al. 2004, Lyytikainen-Saarenmaa and Tomppo 2002). Ant invasions cause huge economic and ecological costs (Holway 2002, Lach and Thomas 2008) and Hymenoptera stings, specifically those of wasps, hornets and bees cause serious allergic reactions and anaphylaxis (Flabbee et al. 2008, Klotz et al. 2009).

Nest cells support heavy weights: bees and wasps
 

Hives of bees and wasps support heavy weights using hexagonal cells in offset positions.

 
  "The hexagonal cells of bees and wasps create an extraordinarily strong space-frame, in particular in the vertical bee comb with two cell layers back to back with half a cell's shift in the position to create a three-dimensional pyramidal structure. The extraordinary strength is exemplified by a comb 37 centimetres by 22.5 centimetres in size, which is made of 40 grams of wax but can contain about 1.8 kilograms of honey." (Pallasmaa 1995:81,101)

"A bees' honeycomb is one of the wonders of the world. Layer upon layer of hexagonal cells of identical size and shape are stacked together as precisely as if the bees had worked to a grid drawn on graph paper. But why should bees build hexagonal cells? Why should they not be square, like boxes, or circular?…As we have already noted, natural organization is economical, expending the least amount of energy and using the least material necessary for a task…Three-way junctions of 120° angles occur quite widely in nature, being the most economical angle for joining things together." (Foy and Oxford Scientific Films 1982:30)
  Learn more about this functional adaptation.

This group of insects contains many subgroups of wasps, and and also bees and ants, which evolved from wasp ancestors.

There are many different sizes in this group. Some parasitic wasps are so small they can develop into adults inside the eggs of other insects. Others are large and strong predators, over 3 cm long. All have chewing mouthparts, and the adults have a thin connection between their last two body sections (the abdomen and the thorax). All have 4 clear wings as adults, with the front pair larger than the back pair (queen and male ants have wings too, but only for a short time. Bees and wasps have straight antennae, ants often have a permanent bend in theirs.

Parasitic wasps often have a very large needle-like structure at the end of their abdomen. This isn't a stinger, its an ovipositor. They use it to inject their eggs inside a host insect, and some drill through bark, wood, or plant stems to get to their victims. These wasps mostly cannot sting, and they do not have the black and bright yellow colors that you may already know about.

Other wasps are predators, biting and stinging other insects and spiders. The wasps eat them, or carry their prey to their to feed their young. Wasps that sting are usually brightly colored with black and yellow stripes, sometimes red. This is a warning to potential predators that they can sting.

Other Physical Features: ectothermic ; bilateral symmetry

Sexual Dimorphism: female larger; sexes shaped differently