full grown larvae will stop feeding and empty their guts of waist in the form of a slushy dropping. do not mistake this for disease it is the normal stage of events prior to pupation . after this the larvae may wander for some time aimlessly before deciding on a place to pupate. in the case of hawkmoths each species/family has its own method of pupation. some species will spin larvae and debris together and make their loose cocoon on the soil surface. others will burrow deeply into the soil and form a subterranean chamber where they will pupate.