How to sex Lepidoptera pupae

[Adam Cotton]

Here is a sketch showing how to distinguish male and female pupae using a magnifying glass. This difference actually applies to all Lepidoptera, although the appearance may be slightly different from group to group. The female (left) has an extra pore on the abdomen when examined with wing cases and legs facing up. This pore often appears just as a partial split in the abdominal segment, and is absent in the male (right).




Adam.

[wollastoni]

Very simple technique and very useful !
Thank you Adam !

[mygos]

Very good technique indeed which I learned in the 70's when I stayed some time at the "Worldwide Butterflies Farm" of Robert Gooden in Sherborne, Dorset UK.

A+, Michel

[Adam Cotton]

I went there several times as a boy in the 1970s too. It was a fascinating place for a teenager who loved butterflies.

Adam.

[mygos]

My friend there was Paul Embden, a specialist in bird-eating spiders !

A+, Michel

[Adam Cotton]

I certainly remember his name, but it was very long ago.

Adam.

[Adam Cotton]

Just as an additional note, I was recently sent some pupae that had been 'sexed' by general appearance and not by using a hand lens. Of those 6 'pairs' 9 were female and only 3 were male.

It is impossible to use size and shape to determine with any accuracy the sex of pupae. There are large & small and thin & fat males, and similarly there are large & small and thin & fat females. Generally females are larger and fatter, but quite often it's just not the case.

I use a hand lens to sex many pupae every day, and like to guess the sex of each pupa for fun as I do it. At least a quarter of the time my guesses are wrong!

Adam.

[clarkt]

Wow. I've been meaning to get around to learning this - because I have about 100 Hemileuca nevadensis pupating now and I want to sex them before I put them up for sale. Luckily they don't spin cocoons so it should be easy for me to examine them. Looking for a strong magnifying glass now....

[Adam Cotton]

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Here is a photo of the tips of two Papilio memnon pupae, male on the left and female on the right. Note the area outlined in red.



The size and length of the pore in the female is variable, even within the same species.

Adam.

[clarkt]

Hmmm, Adam, that is very subtle. But not foolproof you say?

[Adam Cotton]

Actually if you use a hand lens it is really quite obvious, much clearer than in the photo. The only difference between the sexes is in the one segment I indicated, presence or absence of the pore.

This difference is present in all Lepidoptera, but you need to familiarise yourself with each species, as pupae can look quite different, and the shape of the female pore varies between specimens of the same species (sometimes quite short, sometimes there's a slit across the whole segment) as well as between species, but the principle is the same: male no pore, female with a pore in the position indicated. You will soon get the hang of the difference between sexes, and be able to spot it for different species. The Hemileuca you are rearing will have basically the same difference between sexes. I do know that some of the Saturniid breeders will deliberately cut open the cocoons, check the sex of the pupae and put them back inside. If done carefully it has no effect on the pupae at all.

I'm not sure if this applies to Hemileuca, but many Saturniidae pupae are even easier to sex because the male antennae are much more pectinate than the female ones, and this can be seen clearly on the pupa.

Adam.

[clarkt]

May 17, 2015 13:40:31 GMT Adam Cotton said:

I'm not sure if this applies to Hemileuca, but many Saturniidae pupae are even easier to sex because the male antennae are much more pectinate than the female ones, and this can be seen clearly on the pupa.

Adam.

Right you are! I forgot about that.

[ddobermann]

Hi, 

I realise this is quite an old thread but am wondering if there are any insights into sexing pupae from Cirina Forda/Cirina Butryospermi? 

Thanks!

[Adam Cotton]

Mar 27, 2017 12:57:23 GMT ddobermann said:

Hi, 

I realise this is quite an old thread but am wondering if there are any insights into sexing pupae from Cirina Forda/Cirina Butryospermi? 

Thanks!

Since these are silk moths of family Saturniidae they should be relatively easy to sex as pupae. The female pupa will have an extra pore compared to the male one, and also if the antennae of male and female adults are different (in many species the males have much broader antennae) you should be able to see this difference in the pupal case.

Good luck,
Adam.

PS. When you write a scientific name the genus name starts with a capital letter but the whole of the species name is written in small letters. Thus your species are Cirina forda and Cirina butryospermi. It is normal to use italics for scientific names, but not essential in a forum like this.