The discovery of a single incidence of termites in a house at the north end of Big Spirit Lake last summer was the first confirmed report of termite activity in Dickinson County. This brings to 94 the number of Iowa counties where termites have been reported. In other words all but 5 counties have had activity by termites reported at one time or another. In spite of the widespread nature of termites in Iowa, they remain a spotty and highly localized pest. That is, termites vary greatly from place to place, not only within the state but within a county and even within a neighborhood.
Much of our knowledge of termite activity in Iowa goes back to the era of the late Dr. Harold "Tiny" Gunderson, ISU Extension Entomologist from 1936 till his untimely death in 1971. "Tiny" and his colleagues were very good insect collectors and good record keepers. Thus we have an accurate account of where termites were known to occur. Our knowledge was most recently updated in 1988 when a survey of County Extension Directors and local pest control operators was conducted. The combined results of collection records and the survey confirmed the generally-assumed assumption that "termites are present in almost every county in Iowa."
In general, termites are most common in the southern half of the state, with activity rated as "low" in the northern half by the US Forest Service. However, exceptions do occur, often within short distances. Some northern counties, especially counties with major urban areas and major rivers have moderate to high levels of termite activity. Meanwhile, southern counties such as the south central counties of Clarke, Lucas, Monroe and Wayne report little or no termite activity. In these and many of the northern counties (indicated by coarse hashmarks in the accompanying figure) termites have been collected at some time in the past, but levels are apparently at such low levels that the local extension staff is not receiving questions about them.
For more information about termites, refer to pamphlet Pm-1496, "Selecting a Termite Service." Anyone with information contrary to what is indicated here is encouraged to contact me so our information can be corrected and updated.
Termite Distribution in Iowa, 1995
This article originally appeared in the December 8, 1995 issue, p. 156.