Richard H said:
Hi Richard,
A 'Nads Job' is coloquial slang for a genitalia preparation. In every Butterfly and moth species, however similar they are in external appearance do differ in the structure of their male and female sexual organs.
In many cases, it is the only way to identify positively which species it is. Whilst British Butterflies are simple to identify by their wing patterning it is not always so simple with moths, especially when they are subject to great variation in colour and pattern. It is an easy way to separate for example, the Winter Moths, the Daggers, the Ear Moths, and Brocade moths. It is also very useful for identifying Pugs, especially melanic forms that cannot be determined easily any other way. Large insects are very easy to do, Nepticulids are exceptionally difficult, due to their minute size.
It is not a difficult job to do provided you know the correct proceedure, have the necessary equipment and chemicals for microscopical preparation. There are a series of books on the genitalia of both British Butterflies and Moths and the male and female genitalia are figured. There are some species missing but only because they have been found in Britain after the books were published. Drawings for these are usually included in the entomological literature where the species was notified as having been taken in Britain.
One advantage of this method of identification is it can be done on a specimen of any age. I have done work on some specimens that were over 150 years old, in museum collections.
Under a microscope they look very beautiful and in many cases extreamly complex in structure. In several cases in recent decades 'Nads Jobs' has led to the identification of several species including Real's Wood White, Svensons Copper Underwing and Bergers Clouded Yellow to name but three.
Most Scientific Descriptions for newly describes species now include detailed drawings of the genitalia of the new species so other researchers / entomologists can examine specimens they possess to see if the species has been caught earlier but because of it's similarity to another known species has accidentally been missidentified.
In the three species mentioned above it is now known that their larva differ in colour pattern and sometimes shape and the species is easily identifiable if you have a larva. But, if you just have the moth or butterfly then for positive ID you will need a 'Nads Job' doing on it. It's the only way to sort out those species that fall into the 'Aggregate' records.
Harry
