Achemon Sphinx Caterpillar Ecdyses into Fourth Instar

Our oldest Achemon Sphinx caterpillars (Eumorpha achemon) have ecdysed into fourth instar.

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Yesterday, a few of our Achemons entered apolysis and we weren't sure if they were going to ecdyse today or tomorrow, but a few of them did it this evening. There are a few changes in the fourth isntar, most noticeably the body patterns. The white notched spots on each abdominal segment on the lateral sides are very clear and defined now, and there are many small whites spots all over the body, being more numerous and larger on the thorax. These patterns make the caterpillars more textured and attractive, with the white spots giving the body more definition in our opinion. Another change is the body color -- this is the instar in which color variants ranging from green, orange, red, brown, to grey begin appearing.  All four that ecdysed today are in the orange-brown range, each varying slightly in shade. Interestingly, they were completely green when teneral, and the color change came with the melanization afterwards. Almost all the other caterpillars are in apolysis and will ecdyse tomorrow, so we're hoping to see other color variants. A few other changes in the fourth instar are that the thorax is now very thick and will likely become thicker as the caterpillars grow, and the horn, though still quite long, is shorter in relation to the body, and the button like dot at the base is larger and silver in color. 

These fourth instars spent just 5 days in the third instar from 9/22-9/25 and have already caught up with the Opthalm Sphinx caterpillar which also ecdysed into fourth instar today. The Achemons spent just 4 days in second instar from 9/18-9/22 and 6 days in first instar from 9/12-9/18, making it the fastest growing Sphingid relative to its size that we have reared so far. 

- Alan