In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many forms of polymerization and different systems exist to categorize them.
The thistle caterpillar is the larval stage of the painted lady butterfly. The adult insect migrates into Iowa each year from Texas and Mexico. Eggs are laid on both thistle and soybeans. The caterpillar is easily identified by the spines that resemble Christmas trees that have lost all their needles.
Hyphantria cunea Drury. The fall webworm is a widely distributed native pest of shade trees and shrubs and appears from late summer through early fall. It feeds on almost 90 species of deciduous trees commonly attacking hickory, walnut, birch, cherry, and crabapple.