Starr County Butterflies
7-28-08, egg
8-13-08, early instar
8-17-08, on the move
8-19-08, with recently shed skin
8-23-08
8-27-08
8-28-08, full grown
Tragedy strikes - perhaps a fungus causes pupating cat to dissolve, 8-30-08
Ornythion Swallowtail caterpillars are very similar to Giant Swallowtail caterpillars, and both species use my Mexican Lime tree (Citrus aurantifolia). The following observations are very tentative (based on only 2 Ornythion cats), but may help identify the caterpillars. The earliest instars of Ornythions may be more reddish-brown than Giant cats at the same age. The mature Ornythions have that same color where Giants have white; also, their purple spots are larger and more pronounced. From the side, it can be seen that the mature Ornythion caterpillar has four segments of white (see 8-27 picture), while a Giant has only three. The second white segment on the Giant forms a large saddle, while on the Ornythion, the white is mainly on the sides and not on the back.
I observed an Ornythion Swallowtail oviposit the egg shown in the first picture. However, my records are incomplete and I am not sure whether the caterpillar of the study actually eclosed from that particular egg.
This caterpillar, unfortunately, did not survive to become an adult. When it was starting to pupate, fluid began to drain from the body of the caterpillar. It was as if the caterpillar was dissolving. I suspect a fungus or perhaps virus caused this, but I really do not know. I'm glad to say that I have never seen anything like this again.