Although the European corn borer spread to many additional counties of Iowa in 1944 and more than doubled in population in the 20 counties where it was first found in 1942, the damage on individual farms was still not ruinous to any one farmer.
Drake, C. J.; Harris, H. M.; and Blickenstaff, C. C.
"Corn Borer In Threat Stage,"
Farm Science Reporter: Vol. 6
, Article 4.
Available at: http://lib.dr.iastate.edu/farmsciencereporter/vol6/iss1/4