Butterfly Detective

There are many tasks that the Life Sciences department does for the Tropical Butterfly House behind public view. As mentioned in a previous post about pupae pinning, every week we document the numbers of butterflies that are shipped. These are noted in our weekly “Fresh Sheets.” However, one of the more daunting tasks is to identify and record all of those butterflies that don’t successfully emerge to live out their lives in our garden.




As the emerging process is perhaps the most difficult part of a butterfly’s life cycle, not every pupa turns into a healthy and capable butterfly. Some pupae never emerge. Others emerge the wrong way, damaging their wings so they’re unable to fly. Also, we monitor any pupa that have been affected by fungus or parasitoids. It’s important that we record individuals that don’t emerge properly so that we are reimbursed by our suppliers. This information helps them to improve the way butterflies are farmed.


The identification of dead butterflies can be a difficult and tedious job. Our department carries several butterfly encyclopedias and vendor guides to help us with the process. By using visual identification and a process of elimination we are able to identify the specie's country of origin for each individual butterfly. We currently have five active suppliers from which we receive hundreds of pupae every week. In 2009 alone, we received 132 different species of butterflies. You can imagine that for someone with little practice at identification, identifying partially emerged butterflies can be a very long process.


So what do we look for when we identify dead butterflies? The color patterns and designs on the wings are the first identifying marker. You can look at a butterfly’s open wing colors or their closed wing colors. The shape of the butterfly also helps in identifying species. Swallowtails have a tail-like design similar to a fork tail on swallows. Another example is the Longwing butterflies, which have a much longer forewing than hind wing. Measuring wingspan length and body size can also mark a species.


But there are still some obvious challenges. Many butterflies have multiple similarities in design and color. If the wings are in poor condition, this can often make the identification process difficult. When the wings are too damaged we search the thorax and abdomen for identifying markers. Some of the more difficult characteristics can really throw you for a loop. Some species are dimorphic, which means male and female look different. There are many types of butterflies that can also display mimicry, which is defined by a similarity in appearance between two species that protects one or both of those species. Markings can also be regional for a species. It is common for the same species of butterfly to have a series of different designs depending on the different geographic regions of origin.


From an outsider’s viewpoint, it may not seem like a critical task but in actuality it is crucial to the operation of our butterfly exhibit. This data determines which species have the best emergence rates. That information can influence which species and from which vendors we will purchase from in the future. Most importantly, this data collection allows us to become transparent as a department in Pacific Science Center, as well as an organization answerable to the United States Department of Agriculture (USDA). And as our skill in tracking problems with pupae improves, we learn best practices to reduce these very loses. In other words, by knowing what has gone wrong, we are better able to keep butterflies healthy and keep the exhibit looking good.


Therefore, accuracy of this task is important to the future success of the butterfly house. Personally I’ve had moderate success at identifying dead butterflies, but I have noticed that some people have a natural knack for the process. Even though it’s difficult for me, I try to work through this task every week so that eventually I can learn to identify most species with relative ease. So go ahead. Quiz me.

-Adrian Eng, Animal Caretaker & Butterfly Detective