Practice makes perfect - almost! Work on larger species
first to gain experience. Don’t be ambitious, dealing withtiny moths is an art - but things do become easier...

Dissection - Technique

1/ Place the abdomen into a hot solution of potassium hydroxide. Warning! - KOH is highly caustic, boilingmay cause it to leap from the tube and onto your skin or eye! The time taken to digest soft parts will dependon the solution temperature. Once ready, the abdomen will attain a translucent appearance and may tend tosink unless air bubbles prevent it from doing so. It is better to undercook than to overcook.

Tip: A 2 x 3/4 inch glass tube will hold enough solution to do many pugs or
micros. Because of evaporation, top up with water every now and again
2/ Remove the abdomen from the KOH solution with either a hooked pin or a pipette and transfer to a dish or
glass block containing purified water (not tap water!). Under the microscope, use small angled pins or a finebrush to remove as many scales as possible. Using pins, apply gentle pressure and stroking movements to theabdomen to push out the gunk. You should soon be able to see whether you have a female or male, and theprocedures for dealing with each differs.
Tip: Work towards slowly flattening the abdomen, but make sure it isflattened ventral side up or down, not laterally.
The figured example is a coleophorid. In the first image the abdomen is lying on its side and needs to be rolled
over until it’s lying on its back. In the second image, the abdomen has been gently flattened and some scales
have been removed, allowing you to see some of the internal structure. An ovipositor has emerged from theleft-hand side, so this is a female. (It’s often possible to identify the species at this stage.)

3/ Go to.....
FemalesMales

Technique - females
3/ Typically the next stage will involve removing part of the skin. First you should identify the end bearing theovipositor, near to which will be found an opening called the ostium (see Morphology on this site). This partshould remain intact, but the segments beyond can usually be removed. Inside the body will be a bag-likestructure called the bursae copulatrix and from this to the ostium is a tube called the ductus bursae, try not todamage either. Make a cut with a pin or fine scalpel at a junction between two segments below the one
bearing the ostium. Place two angled pins inside the end of the body away from the ovipositor end and slit theskin open until you reach the initial cuts. Remove the skin and hopefully you’ll be left with the ovipositor, thelast segment bearing the ostium, and the ductus bursae and bursae copulatrix.
Photography: This is a good time for a
photograph as alcohol can distort some delicatestructures. The genitalia can be turned in thewater in order to display important details.
4/ The genitalia should now be immersed in a water/alcohol mixture in several stages, for example 30%, 60%
and finally 100% alcohol. This helps the cleaning process and prepares the body for the slide stage. In 100%
alcohol, stain (if desired) can be added. For females, Chlorazol Black (suspended in alcohol, not water) ispreferred. Use only a small amount of stain - overdoing this can mask important features. If you do over-stain,
follow the suggestions on our overstaining page.
5/ The genitalia can now be placed in Euparal mountant on a slide. Alcohol and Euparal will make things
very brittle, so care is needed whilst manipulating the structure. Use Euparal essence if needed to keep themountant runny and to finish off the edges once the cover slip has been placed. Apply the cover slip at anangle to help prevent air bubbles. Small air bubbles usually disappear in Euparal. Label the slide, including areference number to link it to the specimen.

Males

Technique - males
3/ The male organs include the clasping arms and aedeagus, areclustered together at one end of the body - these should by now be
obvious (see Morphology on this site). Hold the opposite end of thebody firmly with the heel of an angled pin and, with a second angled
pin, gently stoke towards the valves. With luck these will float free ofthe body, but may require carefully tearing the skin until they become
detached. If enough scales have been removed, you should see enoughdetail to avoid damaging anything of value.
4/ The skin may be disposed of (although the skin in somefamilies, such as coleophorids and gelechids, have good
diagnostic features). Clean away as much gunk as possible. If theaedeagus is to be removed, do it at this stage. Removing theaedeagus may cause damage, so proceed with caution: lay the valveson their side and hold down firmly with the heel of an angled pin;use a second pin to pull the aedeagus away. Sometimes it isdesirable to evert the thorn-like structures inside the aedeagus (thecornuti), but this can be tricky because of the small size of thematerial. If it must be done, try inserting a small hooked pin into theend of the aedeagus and dragging out the cornuti. Alternatively, slit
open the wall of the aedeagus.
Tip: Refer to a genitalia diagram in a book of the family you are working on and aim to copy what you see
there. In some families it is not possible to detach the aedeagus, or to flatten the valves, or the parts may need
to be presented from a certain angle.
Photography: The aedeagus can be photographed at this stage, before the actions of alcohol distorts it.
5/ The valves should be cleaned of scales and hairs, but stout spines should beleft in place. Carefully open the valves, removing any tissue that prevents themfrom doing so. At this stage, stain with Eosin, Mercurochrome or Chlorazol
Black. Use only a small amount of stain - overdoing this can mask importantfeatures. (If you do over-stain, follow the suggestions on our overstaining page.)
Immerse these (and the aedeagus) in a water/alcohol mixture in several stages,
for example 30%, 60% and finally 100% alcohol. This helps the cleaning
process and prepares the structure for the slide stage. At each stage open thevalves, if necessary turning them upside down and with the heel of a pin press
down on the back against the glass surface. The idea is to use the alcohol’s
stiffening actions to encourage the valves to remain fully open of their own
accord. In 100% alcohol, stain (if desired) can be added.
Transfer to Euparal on a glass slide and if needed re-open the valves. Arrange the aedeagus close by. Apply thecover slip at an angle to help prevent air bubbles. Small air bubbles usually disappear in Euparal. Label theslide.
Photography: Valves are normally displayed flat, but in Euparal small specimens may be able to partiallyspring back, disguising their shape. Consider making a temporary slide for photographic purposes: arrange thevalves on a glass slide with alcohol as a mountant and apply a cover slip, keep feeding in alcohol as it will
evaporate quickly. Once the shot has been taken, carefully remove the slip and apply Euparal to the specimen.

Females