The first Tobacco Hornworm (caterpilar of Manduca sexta) on tomato plants for this year. Found it this morning, 21 Mai, 2014 :
Now, it requires daily inspection and collecting the caterpillars. A single caterpillar can ruin the entire plant. Better more inspections per day.
This
I collected it from a plant , today in late afternoon. It's more mature than the above. The colors are sharper and the horn has the characteristic red color. It is a little bigger too. (Still not very big, both have a little less of 2 inches. They can grow more.)
The green color gives to them an excellent camouflage and are relatively difficult to see.
If you see leaves or green fruit attacked / eaten, look for the caterpillar.
I think, this ear, they appeared earlier than last year. Not sure, but I remember than last year I start to have problems with them only in early June.