By Susan Thurn,
CNHM Director of Education
This week’s Museum Junior Naturalists went out in search of ladybugs. Ladybird beetles, to be precise. This adventure was part of a citizen science project for the Lost Ladybug Project, a search for native ladybugs organized by the Cornell University Department of Entomology. Twenty-six children ages 5-12 donned their insect nets in a field and forest edge along the Namekagon River. We swept above the flowers and plants with hopes of finding ladybugs. We placed a sheet underneath tree branches and gently knocked the branches to observe what fell out of the trees. After a thorough search, we successfully caught ONE ladybug, which promptly flew away. I had thought that an adventurous group of children would be the perfect eyes to spot a ladybug. Now I wonder if they even really knew what they were looking for. Do they, like I did as a child, play regularly with ladybugs?
How could it be that we could only find one ladybug? Three ladybug species, the two-spot, the nine-spot, and the transverse ladybugs were once common but now appear to be rare. Three other species, the parenthesis, spotted pink, and convergent ladybugs, are more common natives. Scientists believe these native ladybugs are disappearing, and the Lost Ladybug Project is using citizen-based science to help find them. Scientists are looking for information on which ladybugs are still present and how many individuals can be found.
While many of the natives seem to be disappearing, ladybugs from other places have greatly increased their numbers and range. Many of us are familiar with the multicolored Asian ladybug, introduced from Japan for biological control of insects. This ladybug has a big appetite, and has adapted to eat the same foods our native ladybugs eat, even eating native and its own ladybug larvae. This is the same ladybug we see in our homes as they winter in huge masses. The checkerspot and seven-spotted ladybug are also ladybugs that were introduced into North America in the late 50’s and 60’s, and their populations continue to spread.
What are the current results of the Lost Ladybug studies? According to the ladybugs being reported, the numbers of introduced ladybugs far exceeds that of the natives. Over half of the findings are introduced ladybug species. Scientists are discovering which habitat niches in which the native ladybugs are the most successful. They are finding that the Asian ladybug is spreading its range into places that wasn’t previously inhabited. Pathogens are being found in native ladybug populations which could be contributing to their decline. Research is showing that native ladybugs that have less food grow into smaller, shrinking adults. Finally, evidence is appearing that the native nine-spot is inter-breeding with the introduced seven-spot ladybug.
Why should we care about ladybugs? They are beautiful. I remember as a child of seven, loving them, catching them again and again and enjoying their tickles across my skin. I learned from a ladybug about how animals use their bright coloring as a warning to predators to remind them of the awful repellents they release when attacked. They are very important because they assist with eating other plant-feeding insects, keeping those populations low. The fewer the ladybugs, the more fragile ecosystems can become during a pest insect population explosion. Keep your eyes open for a ladybug in your own yard. Share your ladybug stories at the Museum’s Nature Watch blog at www.cablemuseumnaturewatch.blogspot.com. Explore and wonder from your own back yard.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and new exhibit, On Lake Owen: The Art of Walter Bohl, in Cable at 13470 County Highway M or on the web at www.cablemuseum.org to learn more about exhibits and programs.