Figures 18–19 in Identification of a new species of Aphis (Hemiptera: Aphididae) based on distinct morphology rather than DNA barcoding

Figures 18–19. Colonies of aphids on their respective perennial host plants. 18) Aphis elena sp. nov. on Pycnanthemum virginianum (L.) T. Dur. & B.D. Jacks. ex B.L. Rob. & Fernald. Photograph: David Voegtlin, emeritus University of Illinois at Urbana-Champaign, Illinois. 19) Aphis monardae Oestlund on Monarda fistulosa L. Photograph: David Voegtlin, emeritus INHS of University of Illinois at Urbana-Champaign, Illinois.