In Abiquiu, NM late one March morning one glorious yellow swallowtail visited my narcissus, grape
hyacinths and my glowing cactus garden. I watched this one butterfly with deep pleasure mixed with concern remembering years of Tiger Swallowtail abundance in Maine. These beautiful insects used to arrive in such numbers … .
Swallowtails have always been one of my favorite butterflies, and over the period of a lifetime I have
raised many eggs to the adult stage. Two mornings ago delighted to see 10 swallowtails “puddling” (the most I have seen in years). Puddling occurs when the swallowtails gather together to drink from small oases that are filled with salt deposits, and I have only witnessed this phenomenon in the spring. For the past two days I have seen them feasting on my rose-like flowering crabapples.
With the catastrophic decline of all insects seeing these beautiful creatures become more of a gift than ever before.
I cannot tell the difference between eastern and western swallowtails but both are found in wooded or
riparian areas.
The ‘tails’ and bright blue and red eyespots that most of the butterflies within this family are adorned with are a form of ‘back to front mimicry’ that helps to confuse visual predators. Birds will strike at these eyespots, and often get nothing more than a fragment of wing, leaving the vital parts of the butterfly unscathed.
All members of this family share most characteristics. Eggs are dome shaped or smooth and globular, and usually laid singly on the host plant. In the Southwest cottonwoods, willow, fruit trees and chokecherry are host plants; in the north, poplar, black cherry, hemlock, fruit trees, chokecherry and alders are favorite egg laying spots. In the garden growing anise, parsley, dill, or sweet fennel attracts this butterfly. One year many years ago I watched a swallowtail feast on my dill before pupating. At that point I took the insect inside so I wouldn’t miss the final transformation. I noticed in New Mexico that the swallowtails loved the abundant wild purple mustard flowers. Here in Maine I see them on my fruit trees and later, on Queen Anne’s lace (wild carrot). The larvae are smooth skinned, and greenish and eggs are laid underneath the leaves. Early instar larvae (term for developmental stages – there are four
in all) often mimic bird droppings. All possess an organ called an osmeterium that discharges a foul scent that discourages visual predators.
One form of protection that all swallowtail larvae use is to manufacture a silken cord and drop off a plant to escape predators. It is estimated that perhaps one in hundreds of eggs laid by each female actually makes it through the four stages to adulthood.
Once hatched the larvae grow rapidly; eating, defecating, and resting in between each molt. The later instar larvae have large inflatable eyespots towards the front end of the body, which supposedly mimic a snake’s head, and presumably warn off visual predators. These are gorgeous creatures.
In about three weeks the caterpillars are ready to pupate and spin a chrysalis around themselves. They will remain in the pre-pupa stage for about a day before becoming swallowtails who rest while drying their wings unless diapause occurs and nothing happens. Diapause is believed to be a ‘risk-spreading’ strategy that these insects use in an environment that may not provide enough host plant material for another generation right away. Diapause allows the developing butterfly to wait until conditions are optimal to complete maturation.
If you ever find swallowtail eggs (the internet has excellent images for the curious) try to raise them. It is impossible to relate how exciting it is to watch this entire process unfold and I recommend it to anyone as one of Nature’s routine miracles.
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