Question: when were fire ants introduced to the us
[{'answer': 'in the late 1930s', 'provenance': [{'wikipedia_id': '36742882', 'title': 'Red imported fire ants in the United States', 'start_paragraph_id': 9, 'start_character': 49, 'end_paragraph_id': 9, 'end_character': 66, 'bleu_score': 1.0, 'section': 'Section::::Economic impact.\n'}]}, {'provenance': [{'wikipedia_id': '36742882', 'title': 'Red imported fire ants in the United States', 'start_paragraph_id': 9, 'start_character': 0, 'end_paragraph_id': 9, 'end_character': 782, 'bleu_score': 0.870548663916591, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18186128418663062941}, 'section': 'Section::::Economic impact.\n'}]}]