Followup Aerial Surveys

To aid beetle control programs, you should make periodic aerial surveys every 4-6 weeks. During midsummer surveys, it is helpful to revisit SPB spots recorded on earlier flights but not yet ground checked or controlled. Remember, because of rapid foliage changes in warm weather, the same spot may look different from the air several weeks after detection. Many spots that first appeared active may by August or September no longer contain yellow-crowned trees. After a followup survey, you may safely assume that such spots have stopped expanding, and give them a low priority for ground checking and control. If all the infested trees in a spot have lost their foliage, the spot can be declared inactive (fig. 8). In winter, however, bare-crowned trees may contain beetle brood and only by ground checking can you verify that SPB spots are inactive.

Some spots that appeared small at first may have grown large by the time of the following flight. If so, you should update their size and ground check priority. For very large infestations, you can aid ground crews by sketching the infestation boundaries on a map or aerial photograph.

Finally, during midsummer flights, inspect recently controlled spots for signs of renewed beetle activity (breakouts). A breakout appears as a group of red and yellow-crowned trees at the edge of the controlled area (fig. 9). Report all breakouts.