Need help with identifying leaf symptoms

Friends,

Greetings from Pondicherry! Our bittergourd friends have been exhibiting the following symptoms on their leaves (pls see attached photo). Looks like something is eating away the ‘flesh’ of the leaves, leaving behind just the ‘skeletal structure’. Would appreciate any pointers to what could be going on. Thanks in advance!

warmly,
Ramji

Pretty sure you would have seen a bunch of small caterpillar larvae voraciously scraping the leaves’ underside.

Given that it is 3-4 days now, I would expect that you see much larger caterpillars that have spread all over the plant - if you have not applied some control measures already, that is.

detection by chandra is absolutely correct.so,you apply avant @1ml/lit+arester @ 1ml/lit as a routine plant protection measure.

Chandra - See a few tiny black specs under the leaves, but no caterpillars at all.

sabujayan - prior to applying anything, would be keen on knowing whats going on.

Am suspecting soil alkalinity, too - our water has shown signs of increased calcium deposits. Wonder whether any of you have thoughts on that? 

Thanks all, for your time.

warmly,
Ramji

Ramji - 3 days is a lot of time for the caterpillars to remain there. You might find some on other parts of the plant - check it out.
The pic is not very clear, but it does look like caterpillar damage.