Looking at the photos below you might be forgiven for thinking that I have put this in the "friend" category by mistake and that "foe" might have been more appropriate. I saw a small grey caterpillar on my Ipomea about a week ago and thought it was a young Convolvulus Hawkmoth. I didn't really check it out properly. Thinking it would be nice to see the moth one day, I let it be. Several more leaves disappeared as did several seeds but I never saw the caterpillar again.
Either this caterpillar likes a variety of food stuff or it doesn't like Ipomea as a convolvulus substitute and is shopping around until it finds something it does.
I still haven't seen that or any other caterpillar since. Nor any other pest either. Just the evidence below.