Question
My "Lagenaria vulgaris" plant is five months old. It grows a lot of flowers - both male and female, but till now hasn't produced a single fruit. The male flowers seem to have been be attacked by some pests, as within a day, they turn brown and on tearing the petals off, few white caterpillars (don't know how to describe them except that they jump when sensing danger) come out from them. As a result, pollen is not produced, and so the female flowers (which don't seem to be affected by those caterpillars) remain non-pollinated, and become black and fall off within a few days... Is there any organic way of driving away these pests so that the plant remains healthy?

Answer
Good day, Abhishek -
I have to say that I have never grown Lagenaria vulgaris (which we call Calabash gourd in the U.S.), so my answer will be limited only to your question about how to combat the larvae that seem to be setting up housekeeping in your male flowers.  

Many gardeners opt for handpicking pests out of their foliage and flowers.  But, in fact, India produces the best organic pesticide around - Neem Oil! Other organic approaches include garlic spray and "Bt" -- Bacillus thuringiensis, which is highly effective and selective against most species of caterpillars. This biological control is a bacterial stomach poison for all caterpillars, which is mixed with water and sprayed onto foliage. It must be ingested by the actively feeding caterpillar, which dies 3-5 days later. It is totally safe to beneficial insects, bees and mammals. Bt is broken down by sunlight within a few days; so repeated applications may be necessary.
You might also consider attracting birds and insects that would feed on these small creatures - assassin bugs, ladybugs, lacewings, and the like are voracious consumers of larvae.

Do the caterpillars seem to evolve eventually into moths or butterflies?  This could be an important clue in how to rid yourselves of them; the so-called "Cabbage White" butterfly in this country is a voracious feeder in its larval form, and I have found that placing eggshells around my plants confuses the adult enough that it seeks other territory to lay its eggs.

I am afraid I have exhausted what I know about this subject, since I have never grown Calabash. I wish I could have been more helpful, and I wish you the best.