Oleander Hawkmoth Caterpillar

Last year she had many of these and not knowing that caterpillars turn into moths/butterflies had collected them all in a bottle and disposed of them. My reaction to the news and constant follow up whether the caterpillars have returned was rewarded today...she came to call me saying she had spotted ONE caterpillar and it could remain...because " How much damage can one caterpillar do?" My offer to translocate it to my garden and my Tabernaemontana plant stands.