Eri Caterpillars Ecdyses into Fifth Instar

​Our oldest fourth instar Eri caterpillars (Samia ricini) have ecdysed into fifth instar.

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After just a day and a half in apolysis. our oldest fourth instar Eri caterpillars ecdysed into fifth instar. Just like after previous molts, the none of the caterpillars ate their excuveae, which is covered in white powder with the head capsule attached as one piece. The fifth instar caterpillars are quite different from the fourth instar caterpillars in a number of ways. First off, the wild powder is completely gone since it was shed off with the old cuticle, giving the caterpillars a very smooth look, though the powder will start to accumulate pretty soon. The body color even without the powder is a yellowish white unlike previous instars in which it was more translucent. Also, there are small pore like indentations on certain areas of the body. The tubercles are longer and tapered, somewhat like the those of Attacus caterpillars and related species, and are very fleshy looking. In addition, the coloration of the tubercles is quite interesting -- the two dorsal rows are tipped with pale yellow and are slightly bluish near the base, the two upper rows of lateral tubercles are the same color as the body, and the lower row of lateral tubercles are tinged with blue. The color of the head capsule,  thoracic legs, and prolegs remains bright yellow, though the base of the prolegs are blue. The circles around the spiracles are still black and are much larger in relation to the body. Size-wise, the fifth instar Eri caterpillars are quite small compared to other Saturniids, only 1.0g which could be the third or fifth isntar of many other species.

These fifth isntar caterpillars spent about 8 days in the fourth instar from 9/12-9/20 which is quite a bit longer than the previous two instars.  Third instar lasted 6 days from 9/6-9/12, second instar lasted 6 days from 8/31-9/6 and first instar was 8 days from 8/23-8/31. 

- Alan