Sunday, July 22, 2018

Ceanothus Silk Moth - part 2

In my last post, Ceanothus Silk Moths part 1, I ended with the middle-stage 3rd instar larvae. This post picks up with the 3rd instar molting to 4th and ends with a mess of cocoons!

Hyalophora euryalus - molting from 3rd to 4th instar (on Pacific madrone)

Hyalophora euryalus - molting from 3rd to 4th instar (on Pacific madrone)
 Note that when the larvae (not just this one but all were like this) molts from 3rd to 4th instar, the six large scoli behind the head are mostly yellow-orange but darken to a varying amount of black around the middle with a coral-colored tip.

Hyalophora euryalus - comparison of 3rd instars (top and bottom) and 4th instar (middle) (on Pacific madrone)
The 4th instar larvae in the middle of the above photo is the same larvae on the right in the photo below and is also pictured in the 5th instar later in this post.

Hyalophora euryalus - early 4th instar larvae (on Pacific madrone)
In the photo above, the larva on the right had the longest scoli of all the larvae feeding on madrone, you will see this in a later picture also when it is in 5th instar. The larva on the left has very small scoli, which will be reduced to almost smooth/non-existent in the 5th instar, compared to these scoli being almost the same length as the six in front on the Douglas-fir-feeding group.

Hyalophora euryalus - early 4th instar larvae (on Pacific madrone)

Hyalophora euryalus - early 4th instar larvae (on Douglas-fir)
Note that the dorsal and lateral scoli are nearly the same length as the front six compared to the madrone-feeding group.

Hyalophora euryalus - late 4th instar larvae preparing to molt (on Pacific madrone)

Hyalophora euryalus - late 4th instar larvae preparing to molt (on Pacific madrone)

Hyalophora euryalus - late 4th instar larvae about to molt (on Douglas-fir)

Hyalophora euryalus - early 5th instar larvae (on Douglas-fir)
Most 5th instar larvae in the Douglas-fir group had obvious black bands and medium coral tips on the front four large scoli (photo above) while some had almost no black and pale coral tips (photo below). The latter was more common in the madrone group.

Hyalophora euryalus - early 5th instar larvae (on Douglas-fir)

Hyalophora euryalus - mid-5th instar larvae (on Douglas-fir)
A couple of the Douglas-fir larvae had tiny black tips on a few of the dorsal scoli, seen in the photo above (towards the rear).

Hyalophora euryalus - early 5th instar larvae (on Pacific madrone)

Hyalophora euryalus - 5th instar larvae (on Pacific madrone)
Remember the 4th instar larva pointed out earlier as having the longest scoli out of all the madrone-feeding group? This is the same larva now in the 5th instar, still with the longest scoli of all the others in the group but significantly shorter than the Douglas-fir larvae.

Hyalophora euryalus - 5th instar larvae (on Pacific madrone)

Hyalophora euryalus - late 5th instar larvae (on Douglas-fir)

Hyalophora euryalus - late 5th instar larvae (on Pacific madrone)
The late 5th instar larvae on madrone were so voracious they not only ate the leaves but also chewed the petioles all the way down to within an inch of the stem!

Hyalophora euryalus - early 5th instar larvae feeding on a Douglas-fir needle
Douglas-fir-feeding larvae grasp each needle with their true legs and munch about halfway through one side of the needle for up to a centimeter, then reach back up to eat the other half, then repeat down the needle until the whole needle is gone.

Hyalophora euryalus - 5th instar larvae closeup (on Douglas-fir)

Hyalophora euryalus - 5th instar larvae closeup of head and true legs, note the multiple tiny eyes! (on Pacific madrone)

Hyalophora euryalus - 5th instar larvae closeup of prolegs, note all the tiny hooks (on Pacific madrone)
Some people think that prolegs (the false legs on larvae, compared to their six true legs that become the legs of the adult) are like suction cups. In fact, they are covered in tiny hooks like the surface of velcro and allow them to grasp just about anything very tightly.

Hyalophora euryalus - mostly late 5th instar larvae, two 4th instar (left) about to molt (on Pacific madrone)

Hyalophora euryalus - late 5th instar larvae (on Douglas-fir)

Hyalophora euryalus - early stages of spinning a cocoon (on Douglas-fir)

Hyalophora euryalus - spinning a cocoon (on Douglas-fir)

Hyalophora euryalus - finished cocoon (on Douglas-fir)

Hyalophora euryalus - all the cocoons, Douglas-fir (left) and Pacific madrone (right) 
Now they sleep until next spring!

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