Attrition in insect development is horrendous with only one or two of every hundred eggs eclosing (hatching into adult form).
I started with about 30 1st instar larvae and have only 4 at 3rd instar. For reasons I don't yet understand, the transition from 2nd to 3rd instar was impossible for most of the caterpillars.
I am deeply saddened by this loss but my brain knows that unprotected outside, there might well be none left.
I have had to revise my theory that all last year's eggs/larvae were lost to Harlequin Ladybird larvae. It's possible it was a combination of Harlequin and difficulty in moulting. I have several of the tiny face/head skins we saw in Adventure 9 which suggests they can shrug off the facial skin and then have major problems moulting the body.
However, all is not lost as unknown to me, Mrs B or her sister/cousin appears to have been busy on my Alder Buckthorn and I have about 15 (protected) 1st/2nd instar larvae.
As you view, top left is 3rd instar to the right a struggling 2nd instar caterpillar. They should simply be able to "walk out" of the old skin.
The bottom images are of newly moulted 2nd instar caterpillars outside under nets.
290518FZ1000500d16f290518
Doggie mummy living in ancient York, Yorkshire, England.
Joined 1st Jan 2018
1st Jan 2024 have achieved 196%
28 March 2024 200%
I take photos, am not a photographer.
Interested...
@fbaileyhttps://butterfly-fun-facts.com/only-1-or-2-butterfly-eggs-out-of-100-live-to-become-adult-butterflies/
See if this link wotsit works. You are of course correct but numbers are declining and the few extras released by people such as myself makes a minimal difference although we like to think we are helping conserve a species. Sometimes we ARE!
jx
The first image was with the back to front lens at almost full magnification. The next 2 with BTF lens at least magnification, the final one with the FZ1000 poking through the nets(One day I might be daft enough to try reversing my macro lens!)
@fbailey Forgot to mention on the first image if you look closely at the bristles (setae) near the "nose", you might see 3 slightly raised and slightly darker spots. Those are simple eyes, 3 of the 6 on each side of the face.
jx
Thanks for the link, nind boggling! Please do reverse your macro, I would be so interested in the resultant images:) x PS So when hatched (or pupated?) the butterflies have only the usual two eyes?
@fbailey Pupation is the process of turning caterpillar (larva) to imago (adult). During this stage, the caterpillar tissues break down and clever enzymes rearrange it all into the adult form.
Eclosion is the hatching/emerging of the adult insect be it butterfly or moth.
Caterpillars have several simple eyes which can basically detect dark or light. Butterflies have 2 kinds of eyes: a simple which detects light /dark & a compound which is able to focus but I'm not sure to what extent. Certainly enough to feed with the long proboscis! Clever stuff, isn't it?
jx
@kali66 Go back to last year:
24 eggs and NO caterpillars.
I blamed the blasted Harlequin larvae which arrived on the unprotected little tree, birds don't help.
Brought caterbugs from the Meadow.
All disappeared.
Brought 10 home at 4th instar stage & put them inside.
Result - 10 butterbugs.
Back to present.
Of about 30-40 eggs, a similar number of 1st instar so brought about 30 inside and protected the tree with a heavy mesh, all I had at the time & better than nothing after I saw Blue Tit approach hungrily.
All went well 1st to 2nd instar, but 2nd to 3rd is very difficult for them & this is where I'm losing them. In theory they should just "walk out" of the existing skin, revealing the fresh wrinkled one underneath. This is not happening.
A few have made the transition but more have struggled and lost. Which makes me wonder how many were lost in the same way last year with Harlequin adding to the attrition.
Does anybody know? Has there been a controlled experiment to determine the truth? I understand that only 1 or 2 of a hundred eggs will eventually fly, enemies are many. It's so sad to see these tiny bodies struggle to free themselves. They manage to free their heads but the skin around their bodies is too tight & hasn't split.
So now I have 4 3rd instar inside which should pass to 4th in a few days. Outside at least 15 2nd instar protected from birds but I can't protect against Harlequin other than by watching carefully,, and i can't help at all if they are unable to moult.
I am learning more every day, it's fascinating and interesting - AND they make excellent photography subjects, now to improve skills to match the models!
Thanks, Kali
j
@kali66 Odd you should say that. I was discussing the problem with a very knowledgeable friend who speculated that the dreadful spring - searing heat followed next day by intense cold - repeat ad infinitum - could have affected one or both of the parents. Or the fact that I was raising them inside from 1st instar, lightly sprayed with water. Unfortunately I don't know of any other people daft enough to spend hours observing caterbugs and their development. The outside larvae are an instar younger and may have different parents. I'm using them as a possibly inaccurate control. I had one poor caterpillar trying to moult who suffered a rectal breakdown during his struggles. The photo is grim but necessary evidence to submit to the 2 men who may have the answers.
I noticed that these sad larvae, instead of "walking out" of their 2nd instar skins struggled and writhed the way 4th instars do as they pupate. Were they trying to pupate 2 stages early? And why did the tiny head/face skins slough off? Questions and more questions and few answers - so far!
j
This is all absolutely fascinating! It would be good to know the answers. But sometimes there just aren't any :( I hope the remaining larvae progress more successfully
@julienne1 Thank you, Julienne. The "Big Four" are doing well and I expect them to transit from 3rd to 4th instar very soon and by June 9th they should be pupating. THAT'S really exciting and looks extremely painful. The outdoor lot seem to be OK, the count varies from 10 to 16, they are good at hiding in plain sight.
I fully agree with your observations. It's watch, study & learn time.
j
@joev The Big 4 have just had their food changed and housing cleaned. They look healthy and almost filling their skins. Moult coming up soon. The youngsters outside also seem to be OK.
Thanks, Joe
j
@gemmabrowne Thanks, Gemma, only 4 remain inside and to my surprise one has started to pupate already, sooner than I expected. It seems OK but given what's happened so far to this batch I'm somewhat apprehensive.
j
June 1st, 2018
Leave a Comment
Sign up for a free account or Sign in to post a comment.
See if this link wotsit works. You are of course correct but numbers are declining and the few extras released by people such as myself makes a minimal difference although we like to think we are helping conserve a species. Sometimes we ARE!
jx
The first image was with the back to front lens at almost full magnification. The next 2 with BTF lens at least magnification, the final one with the FZ1000 poking through the nets(One day I might be daft enough to try reversing my macro lens!)
jx
Eclosion is the hatching/emerging of the adult insect be it butterfly or moth.
Caterpillars have several simple eyes which can basically detect dark or light. Butterflies have 2 kinds of eyes: a simple which detects light /dark & a compound which is able to focus but I'm not sure to what extent. Certainly enough to feed with the long proboscis! Clever stuff, isn't it?
jx
24 eggs and NO caterpillars.
I blamed the blasted Harlequin larvae which arrived on the unprotected little tree, birds don't help.
Brought caterbugs from the Meadow.
All disappeared.
Brought 10 home at 4th instar stage & put them inside.
Result - 10 butterbugs.
Back to present.
Of about 30-40 eggs, a similar number of 1st instar so brought about 30 inside and protected the tree with a heavy mesh, all I had at the time & better than nothing after I saw Blue Tit approach hungrily.
All went well 1st to 2nd instar, but 2nd to 3rd is very difficult for them & this is where I'm losing them. In theory they should just "walk out" of the existing skin, revealing the fresh wrinkled one underneath. This is not happening.
A few have made the transition but more have struggled and lost. Which makes me wonder how many were lost in the same way last year with Harlequin adding to the attrition.
Does anybody know? Has there been a controlled experiment to determine the truth? I understand that only 1 or 2 of a hundred eggs will eventually fly, enemies are many. It's so sad to see these tiny bodies struggle to free themselves. They manage to free their heads but the skin around their bodies is too tight & hasn't split.
So now I have 4 3rd instar inside which should pass to 4th in a few days. Outside at least 15 2nd instar protected from birds but I can't protect against Harlequin other than by watching carefully,, and i can't help at all if they are unable to moult.
I am learning more every day, it's fascinating and interesting - AND they make excellent photography subjects, now to improve skills to match the models!
Thanks, Kali
j
j
I noticed that these sad larvae, instead of "walking out" of their 2nd instar skins struggled and writhed the way 4th instars do as they pupate. Were they trying to pupate 2 stages early? And why did the tiny head/face skins slough off? Questions and more questions and few answers - so far!
j
I fully agree with your observations. It's watch, study & learn time.
j
Thanks, Joe
j
j