Is or are?
Which is correct?
a) There are a caterpillar and two butterflies in the picture.
b) There is a caterpillar and two butterflies in the picture.
The second sentence is correct, i.e.
“There is a caterpillar and two butterflies in the picture.”
It says that you use “a singular form of ‘be’ (which is “is”) when you are giving a list of items and the first noun in the list is singular or uncountable.”
However, “There are two butterflies and a caterpillar in the picture.”, using the general rule “that the verb form matches the item(s) that it is adjacent to …” (Roger Woodham, BBC World Service – Learning English)
However, never use “is” before a plural noun or noun phrase, e.g.
“There’s mangoes on the tree.”
“There’s five apples on the table.”
“Are” should always be used in these kinds of sentences.