It may be the deficiency of water or air moisture in rearing cage. So, when insect eclose from pupa cover, the hemolymph pressure is not enough to unroll the wings.

Thanks Galina, But my another doubt is what the role played by Linolenic or linoleic acid in normal wing development? Can you please help me in this.

I agree with Galina.  Lack of available water and low humidity at the time of emergence are a major cause of wing crippling in both Lepidotera and Diptera. 

One additional factor is dehydration of the pupa during the later states of development which makes it more difficult for the imago to emerge, slowing down the process of escape from the pupal skin, so that inflation of the wings starts before the insect has fully freed itself.  This results in the proximal veins becoming turgid too early, while the distal veins are still folded and the wings crumpled.  The result is that the distal regions do not unfold or inflate correctly.

 i got many references where addition of linseed oil in a synthetic diet solve the problem of wings crippling. I worked on formulation of artificial diet for tea looper and also added linseed oil to get rid of that problem. is there any relationship between lipid-rich diet and normal wing development. please suggest some references Dr. Ian sir.

Dear Anjali, I searched for some information about the role of fatty acids in  normal wing development, but I found only an article about lipidome in Drosophila. It is rather interesting because there is information about different parts of body and role of lipids and fatty acids in their dvelopment. Find it in the attached file.

Dear Anjali

I have run a search on the use of linseed oil in artificial diets for lepidoptera.  There are not many but all say more or less the same thing, that addition of oil (linseed or corn) is important for full wing development.  I have not been able to find the origin of this idea and nobody gives any evidence for the practice.  I suspect that introduction of linseed oil (or some other oil) into the diet was a serendipitous event when the investigator was trying to achieve some other purpose but found by chance that it reduced or minimised wing crippling, especially in males, although this reference looks to be the best targeted investigative study:

https://www.jstor.org/stable/23732265?seq=1#page_scan_tab_contents

I am sure you have viewed the following but if you have missed any I hope they may prove useful:

http://lepidopteraresearchfoundation.org/journals/30/PDF30/30-121.pdf

http://lepidopteraresearchfoundation.org/journals/18/PDF18/18-221.pdf

http://www.ijstr.org/final-print/july2014/Two-Artificial-Diet-Formulations-For-Troides-Helena-Linne-Larvae-lepidoptera-Papilionidae-In-Bantimurung-bulusaraung-National-Park-South-Sulawesi.pdf

http://140.112.100.36/old/chinese/publication/journal/pdf/c0601/c060103.pdf

http://deepblue.lib.umich.edu/bitstream/handle/2027.42/30667/0000311.pdf?sequence=1

Best wishes

Ian

Thank you Ian Sir.. but unfortunately I have all these literature. I agree with your observation, there is no evidence anywhere that how linseed oil reduce the occurrence of crippled wings.