Small part of the popular anime/manga Inuyasha.
These long snake/bug like creatures are known as Shinidamachuu (Dead Soul Insects).
Their soul (no pun intended) purpose is to gather the souls of women for Kikyou. The woman who Inuyasha was in love with 50 years prior.
They wait until the person has died... and when the soul arises to go on its way, its snatched up by the creatures six legs, holding tight to its precious cargo.
However, these creatures are fragile... Inuyasha's tetseiga can destroy them in a mere swipe... no powers whatsoever. So when they collect the souls they must take utmost care as to not be destroyed.
Even in the case of their destruction...
Kikyou sends dozens to collect souls from all over Japan (Maybe elsewhere?)so, many are sure to find souls and return them to her.
But these creature's home and where they came from remain a mystery... much like how Kikyou managed to subdue and control them in the first place.
Many theorys could be placed... like they could be assigned (by default) to guard and protect the bodies of those that Urasue has baked in her demon kiln by making sure that the bodies are well sustained by the souls of the dead, in the event that they might need more energy... like Kikyou, whose large quantity of soul still lies in her reincarnation, that of Kagome Higurashi, the 15 year old highschool student from Tokyo, Japan who came through the Bone Eater's well into the Musashi domain during the Sengoku Jidai era of Japan.