Phenlogy is a study in the correlation between bloom times, degree days, and insect emergence. It is very useful in IPM. IPM is integrated pest management. Integrated pest management is the practice of using biological controls, cultural practices and chemicals to control detrimental insects in your garden with out doing to much damage to the beneficial insects. It excludes the use of blanket sprays which kill everything in their path. Why are we interested in protecting beneficial insects? Mostly because we beneficial insects help us out by controlling the detrimental insects and doing the work of pollinating. Never heard of beneficial insects? There are lots of the them out there. Some examples are, Praying mantis which feeds on insects including aphids. Lady bugs which are cute and also feed on aphids, and adelgids. Honey bees which of course pollinate our fruits, vegetables and flowers while making that delicious golden treat we call honey. There are many important beneficial insects in this world that we simply can not do without. Phenology helps us to pin point which insects are hatching at a certain time so we can time our chemical sprays to not only protect the beneficial insects, but also kill the detrimental insects at the most opportune time. An example of this is scale. Scale insects have a hard shell during the adult phase of their lives, that protects them from weather, chemicals and other predatory insects. When the young hatch out from beneath this protective cover, it is called the crawler stage. During the crawler stage they are moving around on the plant looking for a place mate and then become a sessile adult with a hard shell. The most vulnerable time to spray for certain scale insects like Magnolia scale is right now during the crawler stage. Phenology helps us to determine when that crawler stage is by linking it to something that is easy to see, for example, right now Oakleaf hydrangea, butterflyweed, Greenspire Linden and Queen of the Prairie are blooming. The bugs associated with those blooms are Magnolia scale, Rudbeckia (Black Eyed Susan) psylids, Sycamore lacebugs and Japanese beetle (the adults are out). Having this information at your fingertips will help you to not only spray when needed but diagnose what may be causing problems in your garden. Remember we want the good insects and not the bad. The good insects will help us control the bad. For more information on phenology you can use the internet and Google phenology.