The rothan larva is like most organisms that attack human females. Its behavior is in response to some stimuli that provokes a feeding attempt. Fortunately, in most instances the enzymes cannot digest the alien tissue of the human tho we find it is necessary to void those that use caustic or acid secretions in digestion.
The larva is the free living young of a large freshwater, eel-like creature. It is terrestrial, but it favors swamps and marshes to live in. It hunts as an ambush predator lurking in heavy vegetation for the normal mammalian prey it feeds on.
Tho it is slow and clumsy, it possess a slender whip like tail it uses both to stunt and kill its prey and to defend itself from predators. Then, like the terran starfish, it penetrates the body of its victim with its stomach, thru a convenient opening. In this case, this feeding organ seen above is only the first twelve inches of this organ. The sole sensing organ in thermal and it is likely it is attracted to humans by their body heat.
The toxin is rather harmless to humans and its stinger so small it is only like a small pin prick. Some humans have discovered that penetration can be rather enjoyable and the organisms have proved more than willing to interact with them.
As can be seen, the shaft of this stomach is highly wrinkled to increase its digestive capacity. When inserted in a human anus or vagina these soft folds are intensely stimulating especially as it is wormed around and thrust in and out at it tries to feed. Even move bizarre is that newly hatched larva have long slender stomachs that can slide into the human urethera and are often used for stimulation in this way.
There is a rumor that these are now used in questioning dissidents by Imperial Security. It seems that letting it insert the feeding organ and allowing it to work on the detainee for an extended period can be very effective. We at that lab deny any rumored involvement and feel that this is likely just another rumor, like so many, that have been floating around of late.