MadSci Network: Zoology

Re: Does the wasp go through complete or incomplete metamorphasis?

Date: Thu Apr 20 07:14:44 2000
Posted By: Rob Cruickshank, Post-doc/Fellow, Environmental and Evolutionary Biology, University of Glasgow
Area of science: Zoology
ID: 955665780.Zo

Untitled Hi Jess,

You ask some interesting questions about wasps. In fact there are over 25,000 species of insect which are called wasps, but most of these are extremely small and usually overlooked by all but a few entomologists. I suspect that the wasps that you are interested in are the large social wasps often seen around peoples homes in the summer, often called yellowjackets or hornets. All wasps belong to the kingdom Metazoa (animals), in the phylum Arthropoda (invertebrates with exoskeletons and jointed legs), in the class Insecta (insects), in the order Hymenoptera (ants, bees and wasps).

The different stages in the life cycle of an insect are called instars. All wasps go through complete metamorphosis, and have distinctive larval, pupal, and adult instars. Insects which do this are known as endopterygotes. Their name (endo = within, pterygos = wing) refers to the fact that in larval instars there is no external evidence of any structure which will develop into a wing in the adult. Instead, the future wing tissues are entirely internal and make their first external appearance only in the penultimate stage of the life cycle - the pupa. In contrast, other winged insects such as bugs (order Hemiptera) have external wing buds in instars prior to the penultimate. Another name for the endopterygotes is Holometabola, which refers to the dramatic changes which take place between the larval, pupal, and adult instars. Four of the five largest orders of insects are endopterygotes. These are Coleoptera (beetles), Lepidoptera (moths and butterflies), Diptera (flys) and Hymenoptera, the order to which wasps belong.

Adult wasps are only instar which ever leaves the nests, so if you wanted to see the other instars you would have to look inside a wasp's nest. I live in Scotland and all of the wasps we have here make nests that are completely surrounded by a protective layer, which makes them impossible to see into. The only way to see the preadult stages of these wasps is to dissect a live wasps nest - a risky enterprise, which I have never attempted since, unlike some entomologists, I do not enjoy being stung! If you are lucky enough to live in a country which has native paper wasps (such as the USA or continental Europe), then you could try looking for their nests. These wasps (genus Polistes) make nests which are open and can be seen into. Look on prickly pear (genus Opuntia) in late spring or early summer. I have managed to successfully collect the preadult stages from several colonies of these wasps in southern Spain without getting stung once.

If you suspect that you may be allergic to any kind of sting or bite then never approach a live wasp's nest!

On the other hand, wasps are fascinating insects and please don't be put off by the fact that they could sting you.

Here are a few web sites about wasps which you may find interesting...

Wasps in General
Wasps in the Garden
Social Wasps
Solitary Wasps
Paper Wasps
Social Behaviour of Polistine Wasps


Rob Cruickshank

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