A Little Bit More
Although many different kinds of moth caterpillars have the ability to balloon, we’ve focused on the Gypsy Moth since its a foreign species that has caused major concern for American forests. These moths were brought into the eastern U.S. in 1869 and by the 1920’s were causing localized problems. Gypsy Moths spread to a large area in northeastern U.S. and southeastern Canada causing widespread forest damage as it’s population moved westward and continues to be a problem for North American forests. Today, eastern Wisconsin, Michigan, eastern Ohio and as far south as eastern Virginia are inhabited by this alien invader.
In many years the numbers of caterpillars are not that great in any one location but every so often, caterpillar numbers skyrocket and they actually defoliate (eat all of the leaves) large number of trees in a specific area. An entire hillside may be denuded. The numbers of caterpillars feeding in the trees is large enough that people on the ground can actually hear them chomping on the leaves as a steady rain of frass (caterpillar droppings) falls from above. Even cars have been known to slip and slide on the bodies of caterpillars crawling across the highway during these outbreaks!
Trees can re-leaf after defoliation but this takes additional energy from a tree that reduces its growth and may cause additional stress for any tree already under pressure from insects, environmental pollutants and/or drought. Initially, small caterpillars don’t do much damage. But once they increase in size, their presence is all too obvious when leaves are riddled with holes - eventually these trees begin to look as though they’re just beginning to leaf out. Once they’re larger, the caterpillars feed at night and find nooks and crannies on the tree to rest during the day. It’s at this time that homeowners have an easier way to control the animals. Homeowners can monitor the lower branches and trunks of their yard trees and squash the resting caterpillars each day. This doesn’t remove all of the caterpillars in a tree but it certainly can help to reduce their ravages.
Activities
Science & Social Studies – Alien Invasion
Objectives: Determine when Gypsy Moths may reach your area
Materials: Map of United States, measuring device
I’ve found an online map showing the current range of Gypsy Moths (blue areas) in the U.S. for 2005. Scientists figure that without any reduction in the current speed of expansion, this species will move westward/southward at about 21 kilometers each year.
Take a look at this map and see where the 2005 Gypsy Moth range border line is and figure out how soon before this moth reaches your town. I realize that many of you already have Gypsy Moths so you may want to choose a town where your relatives live outside this zone to try out this exercise.
- Look at the website of the U.S.map (see above address) to see where the Gypsy Moth border is now and correlate that with a rather detailed map of the U.S. Locate your own town (or a relatives town) on the map too that is outside the Gypsy Moth area.
- Now, determine how many miles between the closest area where Gypsy Moths live and your town by using the legend on your map (figure a straight line between the two for measurement).
- Using simple math you should be able to determine how soon Gypsy Moths will reach your town if there are no changes in Gypsy Moth expansion speed of 21 kilometers per year remains constant.
Inquiry Activity you may want to pursue
Can you think of some areas in the U.S. or Canada where Gypsy Moth expansion might slow, if not stop altogether? Using a map that shows the different kinds of habitats across the continent (desert, grassland, eastern forest, southern forest, subtropical, tundra etc), look at the kinds of habitat that the moth is thriving in and see if that changes as their range expands. If it does change, do you think this improves or reduces their expansion rate?
Key Concepts
Behavior and Regulation, Environmental Issues, Identification, Life Cycles, Populations and Ecosystems, Structures and Functions
Questions
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