Sexing larva by pits on belly

[bluemoth]

I found this info in a Lepidopterists Society Journal 1994 Volume 48 Number 3 if you want to read the full article. This method was tested on fith instar larva of Eucheira socialis, Battus philenor, Junonia coenia and Papilio zelicaon. Do not know if this works on moths or other butterfly species. The 9th segment on a male larva has one pit. There are two pits each on the 8th and 9th segment on a female larva. Look on the belly of the larva to find the pits. Use hand lense or scope with 20x magnification to see pits. It was hard to sex P. zelicaon because the pits were pale with no contrasting color. The J. coenia larva could be sexed as early as the third instar. In the female of E. socialis females were esyest to sex between second and forth instar while at the same stages it was almost imposible to sex males. The male E. socials were easyest to sex during fith and sixth instars when the pit was darkened.

If this is found to work on many other species it will be very helpful for those folks who send only male pupa to butterfly exibits around the world.

[Adam Cotton]

It is easy to sex pupae, so I would imagine that exporters would prefer to sex them then since they keep still, unlike larvae. However, it is interesting to know that larvae can also be sexed, sometimes from as early as the third instar.

Adam.

[eurytides]

Adam, is there a general rule of thumb to sexing pupae for butterflies and/or moths? I know it's possible to sex some species, but I'm not aware of a rule that works for all/most.

[Adam Cotton]

Yes, it is basically the same for all butterfly and moth species, although the appearance varies, of course.
When you look at the underside of the pupa the last ring segment of the female has a pore or apparent division in the lower central part of the ring, whereas the same ring of the male is complete.

Here's a sketch to illustrate the principle:






Adam.