Thank you Beth...i just turned over about 10 curly leaves and did not see one aphid. In case they are there and very tiny and maybe green, i rubbed each leaf with my fingers but felt nothing. I did the same to the stems below some curly leaves, but nothing there as well. I will look up "curl leaf aphids", but that doesn't seem to be the problem. Still i will keep an eye out for them.
I wonder if it could be a response to heat, which we have quite a lot of during the day. April and May are normally the hot (mid to high 80s F [30's+ C] and humid months (both day and night), with maybe 10degrees cooler in the night. Now it is hot and dry with much cooler evenings, an unprecedented change in climate, without the humidity. With the humidity, It is the kind of weather that makes seeds and seedlings jump out of the earth busting their buttons to grow...but not this year. Maybe the humidity will show up in May.
I am a big fan of lady beetles and their larvae, we have several different species like the one below (very tiny, tropical). They are so cute with their little yellow legs and behind. Various species always show up when there are aphids in the garden. I have heard that each one, from larva to adult, can eat up to 4000 aphids in a lifetime.