The existence of two types of larvae is described for Phoebis sennae amphitrite; one type is sharp yellow,living on flowers of Sentía; the other type is deep green and living on the leaves of the same plant.Both types of larvae are perfectly homochromous with their respective substrate; it was showed thatthis difference in color does not correspond to a sexual dimorphism ñor that is the origin of sexualisolation.In the laboratory it was observed that it was possible to induce the change in color of the yellow larvae,when reared on green leaves of Senna, change that took place after the following moult; it was alsoobserved that while recently emerged females are able to copúlate, males on the contrary need at leasttwo days of activity after emergence in order to be active sexually.Se demuestra la existencia de dos tipos de larva para Phoebis sennae amphitrite; un tipo es amarillo y se leencuentra en llores de Senna cvmingii (Dicot); el otro tipo es verde oscuro y se le encuentra en las hojas dela misma planta. Ambos tipos de larva son perfectamente homocrómicos en relación al respectivosubstrato. Se demostró que la diferencia de color no corresponde a dimorfismo sexual.En el laboratorio se observó que era posible inducir el cambio de color, las larvas amarillas,alimentándolas con hojas verdes de Senna, cambio que ocurre en la siguiente muda; se observó tambiénque si bien las hembras recién emergidas eran ya capaces de entrar en cópula, los machos sin embargo,necesitaron al menos dos días de actividad después de emerger, para ser activos sexualmente.