Ecological travel is a nuisance for a gardener (8)

I believe the answer is:

greenfly

I'm a little stuck... Click here to teach me more about this clue!

'a nuisance for a gardener' is the definition.
I can't tell whether this defines the answer.

'ecological travel' is the wordplay.
'ecological' becomes 'green' (I've seen this in another clue).
'travel' becomes 'fly' (flying is a kind of travelling).
'green'+'fly'='GREENFLY'

'is' is the link.

Can you help me to learn more?

(Other definitions for greenfly that I've seen before include "Garden pest" , "Common aphid" , "Pests" , "Common aphids" .)

I've seen this clue in The Telegraph.

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