Swallowtail Butterflies Soon to Appear
March 4, 2019
Visitors to Edison Ford during the month of March may notice unusual ‘cages’ in our herb garden alongside the Edison Caretaker’s House! During the last week of February, a large number of caterpillars were spotted on certain plants prospering in this raised bed garden. Upon closer examination, the white ‘saddle’ of the really tiny ones and the protruding orange glands (osmeterium) in response to a light touch on the larger caterpillars, could mean only one thing – a female black swallowtail (Papilio polyxenes) had discovered a compatible habitat upon which to lay her eggs.
It is not often we find such a large collection of caterpillars ‘in the open’, as they usually become prey to birds looking for food to feed their young. At Edison Ford, we relish the opportunity to engage our visitors with nature, so we set out to protect our caterpillars and we hope to raise them exactly where they were found. As one can see in the pictures, two mesh clothes hampers were carefully placed upside down over the plants, with the handles pinned down to keep the hampers from blowing away.
As of March 3rd, the caterpillars range in size from a quarter inch to just over an inch long, allowing an approximate timeline for their next stage (pupating, or metamorphosing into a pupa) to be determined. These caterpillars will shed their skins or molt several times before they complete their growth and are large enough to pupate. Keep an eye out for the “J” formation, which heralds this 3rd stage in the life of the butterfly. The caterpillar will attach itself to a stem by throwing a silk anchor, similar to a harness, which is strong enough to support its weight until the big day arrives. Each stage can last from 9 to 18 days, so a probable timeline for the pupal stage to the emergence of these beautiful butterflies looks something like the table below. Of course, mother nature always has the final say!
- Eggs laid: Between February 18-February 23, 2019
- Larval stage: February 22 – March 22, 2019
- Pupal stage: March 3 – March 22, 2019
- Butterfly emergence: During the 3rd and 4th weeks of March
If you would like to know on which plants the beautiful female Black Swallowtail chose to lay her eggs so that upon hatching, the necessary food was available for her hungry caterpillars, come visit the raised beds adjacent to the Edison Caretaker’s House.