Western Tiger Swallowtail Surprise

During a stopover at my parents' place after a trip to Okanogan County, we were sitting in the shade under an old lilac bush when a huge swallowtail floated by and started hovering around in the upper branches directly above us. I noted that in spite of its large size, it was a Western Tiger Swallowtail (Papilio rutulus) and not a Two-tailed Tiger (P. multicaudata) because the width of the black stripes were very wide. My parents frequently see swallowtails, sulphurs and other butterflies nectaring on the lilac when it is blooming, but it had long gone to seed at this point so we weren't quite sure what this swallowtail was doing because it was hovering from place to place like it was looking for nectar. I moved away from the lilac to get a better look at the swallowtail and observed it appearing to curve its abdomen toward a leaf while continuing to flutter its wings...suddenly the thought hit me, it was ovipositing! I was a little surprised to see it doing this on lilac, as they usually are found on cottonwood, aspen, willow or wild cherry, but I was so excited at the prospect of finally rearing a tiger swallowtail that I didn't think about it much and focused on solving the problem of reaching that high branch.

This particular lilac bush is more like a tree with its multiple 6+ inch diameter gnarly trunks and 20+ foot height. We estimate it is over 70 years old based on the age of the homestead and the knowledge that the lilac was already well-established when the old house was torn down to build the current house. The branch in question was about 14 feet high, but a regular ladder was out of the question because there would be nothing safe to lean it against. I couldn't back my pickup close enough without scratching it...what to do? Dad to the rescue! He fired up his dump truck and had it backed into the lilac in no time, let down the metal panels on the back so we could climb up in it, then set up a six foot step ladder in the bed, which was about four feet off the ground. I was then able to climb almost to the top of the ladder and pull the branch towards me. After a couple minutes of searching I located the leaf and found the egg!

Looking for the Western Tiger Swallowtail (Papilio rutulus) egg on our giant lilac bush. Photo courtesy of Mom, truck and ladder courtesy of Dad :)

Our unconventional setup

Success! Western Tiger Swallowtail (Papilio rutulus) egg on lilac

With egg in hand, I then started thinking that I didn't recall ever reading anything about Western Tigers using lilac as a larval host. A few book and internet searches later, and the only reference to lilac I could find was Art Shapiro's website citing lilac as a host in California. Willow (Salix), poplar/cottonwood/aspen (Populus), wild cherry (Prunus) and ash (Fraxinus) are listed as the hosts everywhere, with sycamore (Platanus), privet (Ligustrum) and sweet gum (Liquidambar) also listed by Art Shapiro. Interestingly, lilac (Syringa) is in the olive family: Oleaceae, which ash and privet both belong to. After talking to Washington lepidopterists, it seems my find is the first record of Western Tigers using lilac in Washington, possibly even anywhere outside of California (if you have recorded them on lilac anywhere, shoot me an email). It is likely that it has just been overlooked all this time, or perhaps they prefer old (i.e. tall) heirloom varieties over more recent varieties that might be less attractive to the butterfly. In any case, if you have lilac bushes, closely watch your tiger swallowtails to see if you notice any strange behaviors around them instead of simply nectaring on the flowers! Now is the time of year to look for tiger swallowtail larvae on all of the hosts listed above - watch for a caterpillar resting in the center of the top of a leaf. Early instars look like bird poop but become a camouflaged green with two large "snake eyes" as they mature. If you find any let me know!

My adorable little cutie-pie, barely a millimeter across with little teddy bear ears

Western Tiger Swallowtail (Papilio rutulus) larva at about 5mm long soon after hatching.

I am rearing it on lilac; a couple 3ft high suckers that Dad dug up from around the base of the old lilac which I then brought home and potted. So far the larva seems to be doing well and has been feeding for about a week now. I'll continue to post photos of it as it grows.

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!