Presentation on scale insects details how they are affecting Sanibel
Rachel Krauss, a biology intern at the J.N. “Ding” Darling National Wildlife Refuge, spent the last few hours of her internship on Friday afternoon delivering a presentation on “Scale Insects on Sanibel: Biology & Distribution.”
Staged at the refuge’s Education Center, her 30-minute program shared information about a wide variety of arthropods, their growth and reproductive processes, where they are commonly found and which plants on Sanibel may be most affected by their presence.
But rather appropriately, Krauss subtitled her presentation “What the heck is a scale insect?”
Scale insects, by definition, are among the group of numerous small insects that are related to aphids. They include many destructive plant pests, in which the males have wings, the females are scale-covered and are often permanently attached to a host plant, and the young suck the juices of those plants.
As a result of their presence, plants populated by scale insects have a tendency to experience yellowing of their leaves, dropping leaves earlier or growing smaller leaves than usual, Krauss noted.
“Upland species of plants are susceptible to scale insects,” she told a crowd of about 20 people gathered at the Education Center. “I found 43 infested plants during my research project, including gumbo limbo, strangler fig, wild coffee and myrsine.”
Krauss also noted that scale insects were most prevalent on gumbo limbo, with approximately 2 percent of those trees within the refuge infested.
“Is it going to affect the gumbo limbo population?” she asked herself. “The answer is no, but it is one additional stressor on them.”
A University of Connecticut graduate in May 2009, where she earned a Masters degree in Conservation and Biodiversity Studies and a Bachelors degree in Ecology and Evolutionary Biology, Krauss joined the refuge as a biology intern in January. Following her presentation on June 24, she had less than two hours remaining on her internship.
“My interest is definitely in insects,” she said. “But my next major decision is whether to go for my PhD in Entomology.”
During her program, Krauss explained the benefits of insects — including crop pollination, medical research, as a food source and plant population control — as well as scale insect effects on Florida’s citrus industry. The most common scale pests found regionally include brown scale, cottony maple scale, Florida wax scale and tuliptree scale.
Krauss also noted that on 42 or the 43 plants she studied as part of her project, ant activity was present. The Florida carpenter ant was found on 86 percent of plants infested within the refuge.
“All of the plants I observed had re-growth this year… a large percent flowered and produced fruit,” she concluded. “A more in-depth study would be needed to correlate scale insect population to plant health.”
In order to manage scale insects on infested plants, Krauss recommended removal of affected branches if scale was present on only one branch, systematic spraying of insecticides or horticultural oils were most effective, some “biological controls” could be used to manage scale populations and removing ants effectively reduced scale numbers by more than 60 percent.
Krauss also suggested that homeowners always inspect plants for evidence of insects prior to purchasing them.