It is a parasitic castrator of small mud crabs in the family Panopeidae, mostly in the Gulf of Mexico, the Caribbean Sea and the eastern Atlantic Ocean.

L. panopaei was first described by the American zoologist Charles F. Gissler in 1884; it was parasitizing the mud crab Panopeus lacustris and was collected at Tampa, Florida.

[2] L. panopaei is native to the Gulf of Mexico, the Caribbean Sea, the Atlantic coasts from Cape Canaveral to Florida and those of Venezuela.

When it settles on a suitable crab host, it pierces the carapace and develops underneath as an endoparasite for about a month.

[3] Female crabs care for their eggs by carrying them beneath their abdomen, keeping them well aerated and protecting them.