So today, someone pointed out a dying Polyphemus moth to me while I was doing my daily photography walk. It was female, so I brought it home to see if it would lay before it finished dying (it had taken some pretty heavy damage from something). It did not. Are eggs fertilized internally, or as they are being laid? I pulled the eggs out of the corpse, but I don’t know if I have any chance of them hatching or not. If they were fertilized I could possibly save a few (I raised some year before last).
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My understanding is moths lay fertilized eggs. The fertilization occurs internally and I’m fairly sure some or all species (can) mate with multiple partners and retain spermatophores from multiple partners. after she uses some of the nutrition and the eggs are fertilized in the bursa they harden into final shape internally before being laid.
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Ok! I hope so. The eggs were firm in the abdominal cavity. I could feel them when i felt from the outside, so when I checked her, and she had ceased all movement, I took her right out, and opened her up. They are all formed. Letting them dry now.
I know they lay fertile eggs, I just didn’t know at what point they were fertilized. I didn’t know if they were fertilized in the main cavity or if the bursa excreted sperm during the laying process. I know very little about internal moth anatomy function, so this is a learning experience! Haha
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I’m a total amateur so I’m learning every second, it’s great!
I recently acquired this book and love it:
https://forum.inaturalist.org/t/current-or-general-favorite-field-guides/656/83?u=mira_l_b
I pulled that tidbit I shared straight out of those pages. If I read it correctly then I think it would be prior to laying. @mamestraconfigurata, can you confirm?
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I’ll add that to my wishlist =p
I’ve been recording my local lepidoptera for some years now, but I’m always excited to learn new things!!!
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I don’t know the book, but it looks great. A long time ago I was told that a male moth ‘builds’ a spermathica (? sp.) inside the female. It’s a little chitinized structure that holds the sperm and is unique to each species. I’ve seen them (again, a long time ago), but do not know if the eggs are fertilised in one batch, or as they are laid.
I some of this up, and, as usual, things are more complex than they seem. https://academic.oup.com/beheco/article/21/4/714/247946 This (https://books.google.ca/books?id=jHUCdbgW4MAC&pg=PA313&lpg=PA313&dq=mechanism+of+moth+egg+fertilization&source=bl&ots=LOFaS_i_bp&sig=ACfU3U2Rov_yLEzgNHIz4Q3ekqd4J9b_JA&hl=en&sa=X&ved=2ahUKEwjy_buG65DqAhU5SzABHdvcAO0Q6AEwEHoECAsQAQ#v=onepage&q=mechanism%20of%20moth%20egg%20fertilization&f=fals) seems to suggest that eggs are fertilized as they pass through the oviduct. Chapman’s book was general for all insects, so I don’t know how accurately it represents moths. I have seen dead, pinned moths lay eggs, though!
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dissecting moth genitalia under a microscope changed my view of the world…I kid you not. I’m awe struck at the complexity of biological functions generally but the odd beauty of insect genitalia (all their parts really) exploded my mind. I still don’t completely understand the functions but am scratching the surface on the parts.
@mamestraconfigurata, thanks for your input. That book is so fabulous and user-friendly without being too dilute and boring or too extremely academic. Highly recommend, new from 2019 ( I think?).
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Not meant to be a joke about scratching, but hey…accidental humor should be respected and let be :)
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Humour is always good! Studying insects, and working with them, also changed my life view of the world. We learn to be focused on vertebrate life that being exposed to the workings of insects is a shock. I would imagine it’s the same for all non-vertebrate life (I did take a course in invertebrate zoology).
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Thanks everyone! They didn’t hatch, so no luck, and at least I tried hahaha.
I’ve loved reading the responses, I love learning how things work!
I also found a female Imperial Moth a week or so ago near the same area. Had jammed herself up under a fence. I don’t know why she didnt get out, but when I pulled her out, she was long dead. Her whole abdomen was stuffed full of eggs! I briefly examined them. Only the outer layer of her body had decayed on the abdomen, and the eggs were still in the cavity. They looked fully developed, which is disappointing that they never got laid.
Oh well, that’s life right? Moths can be strange! I saw a Luna year before last, laying eggs on the side of a building. Brought it home and raised a few. Learned a lot, from eggs that wouldn’t have gotten far obviously hahaa.
Thanks again everyone!
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