Wednesday, May 2, 2012

Looking for Ladies

Love is in the air
I spent last Monday looking for pregnant females... Spicebush Swallowtail (SBS) butterflies to be exact.  As Friends of the Garden gears up for the opening of the Butterfly House at the Botanical Center, the butterfly "wranglers" begin rounding up the livestock.

We are looking for female SBS willing to lay their eggs on spicebush host plants in the Butterfly House.  Once deposited, they can grow into caterpillars and pupate in the relative safety of the mesh walls, away from birds and hopefully parasitic wasps.  The pupae (chrysalis) are then collected and stored to time their coming out as adults for all to see.

Unlike some butterfly species, it is relatively easy to identify female SBS.  On the back of the hind wing they are a deep blue while males have a lighter blue-green coloration.  It is hard for me to detect the females on the wing and apparently the males have the same problem initially as I will occasionally see one buzz another male or even a similarly colored Pipevine Swallowtail before leaving for greener pastures.  The males also can detect pheromones to help them find the ladies.

Swallowtail butterflies tend to continue to flap their wings as they nectar on flowers, unlike most other butterflies.  When the females land on a spicebush or sassafras to lay eggs (oviposit), they will drum on the leaf with their front legs, sampling the plant with chemoreceptors on the tips (think "front feet"). 
Male SBS

SBS are said to cruise at lower levels that other swallowtail species.  By concentrating on nectaring butterflies rather than those cruising rapidly through the woods, I was able to catch only females.  I suspect that those darting around nonstop were males looking for lonely ladies while the females were busy storing up on prenatal nectar.

The older butterflies tend to lose scales and have more tattered wings.  At this time of year, I bring these to the Butterfly House as they are more likely to have mated.  I have released specimens that could barely fly but managed to stagger to the nearest spicebush and immediately start laying eggs, answering the call to motherhood. 

Photography by Dr. Chris Barnhart
The Butterfly House will open on May 11th.

1 comment:

  1. What a wonderful post and pictures, and thanks for the information on The Butterfly House.