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Bees, Wasps and Ants (Order: Hymenoptera)

A photograph of worker honeybees (_Apis mellifera_) on honeycomb.

Honey bee workers clustering on a honeycomb.
Photograph by Waugsberg, used under GFDL.

Introduction

The most familiar Hymenoptera are the bees, wasps and ants; insects feared by many people because of their stings. However, these make up only a small proportion of the order. The Hymenoptera also includes Ichneumons and other parasitic "wasps" and Sawflies. Unfortunately, there is no English name to embrace the whole order as there is for beetles, bugs and true flies.

Hymenoptera characteristically have two pairs of wings, a large fore pair and a smaller hind pair. These wings are held together by a series of hooks (called a frenulum) and may appear like a single pair to the naked eye. Hymenoptera also tend to have prominent antennae, generally with nine or more segments and biting mouthparts.

The most conspicuous Hymenoptera are the fast-flying, often black and yellow, bees and wasps. Ants, too, are easily noticed when intruding on our lives. However, many of the smaller and less familiar Hymenoptera can have a jewel-like beauty on close examination and are interesting in a great variety of ways.

In the British Isles, there are at least 6,700 species of Hymenoptera, occurring in all terrestrial habitats. On a world scale are at least 100,000 species, so this is only a brief introduction to the group and deals mainly with the main British groups.

Hymenoptera and Man

Honey

Honey is associated with all manner of positive things; so often so that it is easy to forget that it is regurgitated by insects! A concentrated form of flower nectar stored by certain bees for their young, honey has been sought since earliest times. There is a 9000-year-old cave painting in Spain depicting the gathering of wild honey and beehives are illustrated on friezes in ancient Egyptian tombs. Honey bees are also valued for their beeswax, royal jelly (used to supplement the diet of developing queens) and other products. Find out more about bees and beekeeping.

Pollination

Many winged Hymenoptera visit flowers. Bees do so to collect pollen and nectar for themselves or to provision their developing young, while wasps are often on the lookout for other insects to prey upon. Flowering plants have, in an evolutionary sense, taken great advantage of this by offering nectar to insects most likely to carry their pollen to another flower. With many important crops dependent on insect pollinators, Hymenoptera have a huge role to play in feeding the world's human population. Bumblebees are routinely introduced into commercial greenhouses where pollinators are in short supply, and the contribution pollination makes to the world's economy is tens of billions of dollars per annum.

Pest control

A photograph of a parasitic wasp, _Peristenus digoneutis_, preparing to lay an egg in a tarnished plant bug nymph.

A parasitic wasp, Peristenus digoneutis, laying an egg in a plant bug nymph.
Scott Bauer, USDA

Wasps are a gardener's best friend killing countless garden pests. In fact, Ichneumons and other Parasitica are used as successful biological control agents. For example, the parasitic wasp Habrolepis dalmanni (Encyrtidae) was introduced from North America into New Zealand for the control of Golden Oak Scale insect Asterolecanium variolosum (Hemiptera:Asterolecaniidae), a serious pest of oak. Ants are also valued in some forests for their role in controlling pests in large numbers.

That said, not all Hymenoptera are quite so welcome. The larvae of Sawflies and Wood Wasps damage crops and ants can encourage aphid blooms by protecting the aphids from predators.

Life Cycles

Life stages

Hymenoptera undergo complete metamorphosis - that is, they have an egg, larva, pupa and adult stage. The larvae are usually soft and white with no legs, looking similar to diptera larvae; the larvae of some Sawflies have small fore and hind legs like caterpillars.

The sexes are separate, but males are rare in several Parasitica, and the sexes are "redefined" a little in the social aculeates. Many Hymenoptera are protandrous, that is the adult male starts to emerge before the female, awaiting the emergence of females to mate with or even mating before or while she is trying to emerge. In contrast, females of some Parasitica will wait for their own male offspring to emerge before promptly mating with them!

Types of life cycle

There are a bewildering variety of types of life cycle among Hymenoptera. These are intimately bound up with the way in which food is provided for the offspring.

In the Symphyta, eggs are laid in plant tissue and simply abandoned. Other plant-feeding Hymenopterans, such as the Gall Wasps (Parasitica), induce plants to grow protective structures (galls) that shelter the young as they feed. In the Parasitica, and some aculeates, parasitoid life cycles are common. Parasitoid larvae behave like parasites, feeding off the tissues of living animals, but unlike true parasites usually kill the host at the end of their development. Parasitoids are often extremely specialised, attacking only a single species. When this itself is the larva of a parasitoid insect, they may be called hyperparasitoids.

Nest-building is well-developed in the aculeates, with social organisation being a special case. Solitary, as opposed to social, aculeates may build one or more nests, each supplied with food for the larvae. Other Hymenoptera take advantage of the hard work done by others to supply food. This is known as kleptoparasitism, and the species are often called "cuckoo wasps" or "cuckoo bees". Eggs are laid on another species' store of food, which is eaten by the developing larva, usually killing the rightful heir in the process. There are even social kleptoparasites, in which a whole colony of bees, wasps or ants is taken over from within by another, often closely related, species.

Social Organisation

The phenomenon of sociality among insects is best developed among the aculeate Hymenoptera (it also occurs in termites and a single mammal, the naked mole rat).

Social animals, in this sense, are those in which individuals have evolved different reproductive roles, with at least two types (castes) of female (a fertile queen and sterile workers) that co-operate in raising the young.

A social colony is like a single organism in that it has a single set of genes to be passed on at reproduction, in the form of a new queen or queens. In the most advanced cases, seen in ants, some bees, and some wasps, the different castes are strikingly different in appearance from one another.

It is in these groups that many fascinating co-operative behaviours have evolved, for example, the paper-making habits of wasps, the waggle-dance communication of honeybees, and the seemingly suicidal defence of colonies by workers with no reproductive interests other than that of the colony as a whole.

The apparent selflessness of honeybees still inspires admiration, as it did to Shakespeare's Henry V: Creatures that by a rule in nature teach / The act of order to a peopled kingdom. It is only since Shakespeare's time that it became widely known that bees have a queen and not a king; and more recently still that the complexities of hymenopteran societies have begun to be fully appreciated.

Diversity and Classification

The Hymenoptera are divided into two suborders, the Symphyta (Sawflies and their relatives) and the Apocrita (species with a thin "waist" including all the wasps, ants and bees). Within the Apocrita, there are two groups, the Parasitica (the most diverse of all Hymenopteran groups) and the Aculeata, species that have modified their egg laying tube (ovipositor) into a sting. The list below summaries the groups that are dealt with in this introduction to the Hymenoptera, although there is not space here to go into the full classification and evolutionary history of the group.

Essential reading from the Amateur Entomologists' Society

Resources

Related links: Bees, Wasps and Ants (Order: Hymenoptera)

Books

Hymenoptera in general

Gauld, I.D., Bolton, B., Huddleston, T., Fitton, M.G., Shaw, M.R., Noyes, J.S. , Day, M.C., Else, G.R, Fergusson, N.D.M. & Ward, S.L. The Hymenoptera. British Museum (Natural History) Oxford University Press, 1988.

Bethyloids

Perkins, J.F. Hymenoptera Bethyloidea (excluding Chrysidae). Handbooks for the Identification of British Insects, 6, Part 3(a). London: Royal Entomological Society, 1976.

Ants

Bolton, B. & Collingwood, C.A. Hymenoptera, Formicidae. Handbooks for the Identification of British Insects, 6, Part 3c. London: Royal Entomological Society, 1975.

Skinner, G.J. & Allen, G.W. Ants. Naturalists Handbooks 24. Slough: Richmond Publishing Co Ltd, 1966.

Cuckoo Wasps

Morgan, D. Cuckoo wasps (Hymenoptera, Chrysididae). Handbooks for the Identification of British Insects, 6, Part 5. London: Royal Entomological Society, 1984.

Spider Wasps

Day, M.C. Spider wasps (Hymenoptera:Pompilidae). Handbooks for the Identification of British Insects, 6, Part 4. London: Royal Entomological Society, 1988.

Social Wasps

Else, G.R. Identification. Social wasps. British Wildlife, 5, 304-311, 1994.

Potter and Mason Wasps

Archer, M. E. The British Potter and Mason Wasps. A Handbook. Published by the author, 2003, 2nd ed.

Solitary Wasps

Lomholdt, O. The Sphecidae of Fennoscandia and Demark. 2nd edition. Fauna Entomologica Scandinavica, 4. Leiden: Brill, 1984.

Richard, O. W. Scolioidea, Vespoidea and Sphecoidea (Hymentoptera, Aculeata). Handbooks for the identification of British Insects, 6. Part 3(b). London: Royal Entomological Society, 1980.

Yeo, P.F. & Corbet, S.A. Solitary wasps. Naturalists Handbooks 3. The Richmond Publishing Co. Ltd, 1995, 2nd ed.

Bees

Else, G.R. In prep. Handbook of the bees of the British Isles.

Perkins, R.C.L. The British species of Andrena and Nomada. Transactions of the Entomological Society of London, 1919, 218-319.

Perkins, R.C.L. The British species of Halictus and Sphecodes. Entomologist's Monthly Magazine, 58, 46-52, 94-101, 167-174, 1922.

Perkins, R.C.L. Notes on some aculeate Hymenoptera, with corrections of errors. Entomologist's Monthly Magazine, 67, 20, 1931.

Saunders, E. The Hymenoptera Aculeata of the British Isles. London: Reeve & Co.Ltd, 1896.

Bumblebees

Edwards, M. & Jenner, M. Field Guide to the Bumblebees of Great Britain and Ireland. Published by Ocelli Ltd.

Prys-Jones, O. & Corbet, S.A. Bumblebees. Naturalists Handbook 6. The Richmond Publishing Co. Ltd, 1991, Second edition, revised.

Sawflies

Benson, R.B. Hymenoptera: Symphyta. Handbooks for the Identification of British Insects, 6, Part 2(a). London: Royal Entomological Society, 1951.

Benson, R.B. Hymenoptera: Symphyta. Handbooks for the Identification of British Insects, 6, Part 2(b). London: Royal Entomological Society, 1952.

Benson, R.B. Hymenoptera: Symphyta. Handbooks for the Identification of British Insects, 6, Part 2(c). London: Royal Entomological Society, 1958.

Wright, A. British Sawflies a key to the adults of genera occurring in Britain. Field Studies Council, 1990.

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