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Wasps and bees are insects that belong to the order Hymenoptera. Most adult
wasps have four membranous wings, which makes it easy to distinguish them from beetles,
butterflies and flies. Their life cycle consists in four stadia: egg, larva, pupa and imago.
Most people are familiar with the social wasps, which may ruin the pleasure of a countryside
picknick in late summer. In fact, for most people the very term wasp only refers to
the social wasps. But despite their well-knownness, the social wasps form but a small minority
within a hugely diverse group of insects. For instance, ants are in this group, too, and so
are bees. And while the honeybee is familiar to all of us, there are literally hunderds
of bee species, some of which would never be recognised as such by the vast majority of people.
Moreover, bees and ants are just two familiar groups within the wasps. There are many more groups
within the wasps, often equally diverse, but mostly little known because of their small
size. All in all, taxonomically the term wasp covers a large spectrum of insect families.
To come to grips with this huge diversity, it helps to outline the major groups first. Once you
have acquainted yourself with the broadest subdivisions, it becomes more easy to deal with the
lower levels of classification (say that of the family and below). Using a classification is a
bit like using a map: first you find the main ways, than the back alleys.
There are two major groups of Hymenoptera: the Symphyta and the Apocrita (see
the small gallery below for representative examples). The Apocrita are defined by the presence
of the so-called wasp waist. Their first abdominal segment has become incorporated into
the thorax, together forming the mesosoma. The remainder of the abdomen, the metasoma, has a
narrow connection to the mesosoma. It is this narrow connection that is referred to by the term
wasp waist. The wasps lacking this feature are referred to as the Symphyta, but nowadays
biological groups may no longer be defined by the absence of some character. Therefore, Symphyta
has lost its formal status as a bona fide division of the Hymenoptera. Nevertheless, it is still
practical to use this term in a descriptive sense.
The Apocrita themselves again consists in two large groups, the Parasitica and the
Aculeata. Here the same problem raises its head: the Parasitica are non-Aculeata Apocrita.
That is, the Parasitica are defined by the absence of certain features, rather than by the
presence of some feature. For this reason, the taxon Parasitica is not taxonomically valid,
just as the Symphyta. Nevertheless, sometimes it is practical just to neglect taxonomic niceties,
so for convenience I will use the term. The Parasitica are the most speciose group of the Hymenoptera,
and as their name suggests, part of there life cycle is parasitical. Their larvae are parasitic
on other insects. One way to distinguish Parasitica from Aculeata is to count the number of antennal
segments; for most Parasitica this number exceeds 13, while in the Aculeata this number amounts to 12 or 13.
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