Effect of Herbicide Maintenance of an Electric Transmission Line Right-of-Way on Butterfly Populations

"A study was carried out in 1997 of the butterfly populations on the right-of-way of a 230-kV transmission line of GPU Energy in the Allegheny Mountain Physiographic Province of central Pennsylvania. The objective was to determine if herbicide spray maintenance had produced an adverse impact on butterfly populations. Butterfly counts were made at 7 points in time during the growing season to coincide with flowering of important plant species. On the handcut control unit, there was a total of 14 butterfly species and 58 individuals present over the growing season. In contrast to this, there was a total of 20 butterfly species present on the high-volume basal spray unit, 19 species on the mowing plus herbicide spray unit MH-1, and 22 species on the mowing plus herbicide spray unit MH-3. The number of individual butterflies ranged from 172 to 186 on the 2 mowing plus herbicide spray units to 342 on the high-volume basal spray unit. These results indicate that herbicide spray maintenance had not produced an adverse effect on butterfly species and number of individuals compared to handcutting without herbicides."