Hymenoptera - the bees, ants, wasps (social and solitary) & saw flies

Fast facts about Hymenoptera

  • Two pairs of membranous wings, the front pair usually larger.
  • Forewing and hind wing attached by a row of minute hooks on the front edge of the hind wing.
  • Bees, ants and wasps have chemoreceptors for taste and smell on their antennae as well as on their mouthparts.
  • Split into two groups; Symphyta (saw flies and wood wasps) which have no "waist", and Apocrita (bees, wasps, and ants) which have a distinct narrow waist.
  • All species of ant, some species of bee and wasps are social insects. Apart from the termites all the social insects are in the Hymenoptera order.
  • Around 150,000 species worldwide, over 16,000 in Europe, and around 6,600 in British Isles.
  • There are around 20,000 species of bee world wide, and around 3500 species native to the USA, and 270 species in the U. K.
  • Hymenoptera appeared about 200 million years ago.
  • Recently a 100 million year old bee was found fossilized in amber. Preliminary studies of this bee confirm the belief that bees are descended from wasps.
  • Honeybees have been used by man to pollinate crops for over 4000 years. In the U. S. A. alone they pollinate almost 100 different crops for us.
  • In the U. S. non-native honeybees pollinate $15 billion of crops every year (2000).
  • In the U. S. native bees pollinate crops worth about $3 billion every year (2006).
  • "Killer bees" are a hybrid of two honeybee species - one from Africa and the other from South America.
  • The "industrious ant" is a myth. It is normal for 50% or more of the adult ants in an ant nest to be idle at any given time. And male ants contribute virtually nothing to the nest.
  • Bees evolved from wasps around 130 million years ago.
  • One third of the food eaten by humans comes directly or indirectly from crops pollinated by bees.
  • Click for the bumblebee pages.
  • Click here for mason bees, leaf cutter bees, carpenter bees and other bees
  • All Hymenoptera are haplodiploid, i. e. the females develop from fertilized (diploid) eggs, and the males from unfertilised (haploid) eggs. So male Hymenoptera have no father.

Evolution from wasps to bees

About 130 million years ago, when the first flowering plants evolved, it is believed that some wasps diversified and started feeding their grubs on pollen which is full of protein and highly nutritious, instead of their usual diet of chewed up insects. And it is believed that these wasps evolved into the bees.

Wasps

There are more than 110,000 species of wasp described (2020). They can be roughly divided into two groups, those that can sting and are predators of some sort (around 30,000 species), and the rest which are parasitic. The wasps that sting can be further divided into the social and the solitary.

The social wasps come in for a lot of bad press, and get little credit for all the good things they do, e. g. after birds and spiders it is the social wasps that are the most important predators of the pest insects (caterpillars, aphids, bugs and flies) on our crops. A mature wasp nest needs around 3 - 4000 insects a day to feed the grubs. In a typical summer in the U. K. it has been estimated that wasp larvae eat around 14,000 tonnes of insects! Also many orchids can be pollinated only by wasps.

Wasps do sting though. An average wasp sting pumps in around 15 microlitres of venom. The venom includes histamines that increase blood flow, proteases and lipases to rupture the flesh and blood cells, and if that were not enough neurotransmitters that overstimulate the nerves. Multiple wasp stings in a human can cause nausea, vomiting and confusion. More than 100 sings requires rapid emergency help, and few humans could survive 1000 stings. Multiple stings are usually caused by disturbing a nest, so treat wasp nests with caution.

Paradoxically, as with bee venom research is ongoing to investigate the medical properties of wasp venom. Polybia paulista, a large, black Brazilian wasp has an active ingredient in its sting that kills cancer cells in mice. Other active ingredients are being researched for antibacterial and antiviral properties, allergy treatments, cardiovascular disease treatments and neurological condition remedies.

Social insects have three major traits

1. Individuals of the same species co-operate in caring for the young.
2. There is a reproductive division of labour.
3. There is an overlap of at least 2 generations in life stages capable of contributing to colony behaviour.

Common behaviour in social insects and humans

This is a short list of some of the common behaviours some social insects share with some humans.

Of course social insects were doing all these things long before humans existed. We have been around for just a million years or so, a blink of an eye in the history of life on Earth.

Bees, flowers, nectar and honey

Bees, whether social or solitary, eat pollen and nectar all their lives. So bees need flowers, and many flowers cannot breed without the pollinating ability of bees. In California every year about 1,000,000 hives (about 10 billion bees in all) are transported in from other parts of the US just to pollinate the almond crop in February.

Plants reward their pollinators with nectar - it has no other use. Most bees carry the nectar in their stomach (bumblebee honeystomach) and regurgitate it in the nest or hive.

Some species store the nectar, which with the evaporation of some water and the addition of enzymes from the bee's stomach, becomes what we know as honey.

Pollen is carried home either in pollen baskets on the bee's hind pair of legs, or on thick hairs on the undersides of the abdomen, as in the leafcutters.

The Apis mellifera (honeybee) genome has been published recently. It is the fourth insect to have its genome sequenced, the others are the mosquito, fruit fly and the silk moth.

The colour of honeybees varies according to the species, but is usually brown and covered in brown/gray hairs. The honeybee is not nearly as hairy as the bumblebee. The body of the queen honeybee is similar to that of the workers, but she is a little larger.

Bees were sacred to the ancient Egyptians. They believed bees descended from the tears of Ra, the sun god, as he landed on earth. The bee was a symbol of kinship, and jars of honey were placed in tombs to aid the journey of the departed into the next life.

Bee antenna

bee antenna

The drawing above is the antenna of a female bee, the male antenna is the same except it has an extra segment on the flagellum.

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