What has worked for me specifically for dionaea ( venus fly traps) is to submerge the plant completely in rain water for one day.
You maybe will have to repeat this until the aphids have all died. The first time will kill most but sometimes eggs will hatch later on so the chances
are there could be more aphids. Look mostly under the leaves and on the stem .. that's where they like to hide.
With a magnifying glass you can easily see them .. I used my iPhone with a magnifying app to take the photos.