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.
SUBPHYLUM CHELICERATA, CLASS ARACHNIDA. Spiders. This group contains many familiar organisms, including the spiders, mites, scorpions and ticks. Examine the large spider on the right. Again, notice that there are two body regions, a cephalothorax and an abdomen. On the cephalothorax are two to four pairs of simple eyes.