— by Dr. Jeff Whitworth and Dr. Holly Davis
Alfalfa fields were again sampled 18 April, after the latest bout of sub-freezing temperatures. Alfalfa weevil larval development does not seem to have progressed much since fields were sampled last week. All larvae that were collected from plant terminals were still small, 1st instar larvae. Like the last two week’s samples, there were live 1st instar larvae feeding beside dead larvae. However, a few larger, 2nd instar larvae were found in the leaf litter under the alfalfa canopy. Infestation levels varied considerably depending on location. Open fields with exposure to wind had infestations ranging from 0% (no live larvae found) to a maximum of 10%. However, one small alfalfa field that was bordered on the north by a windrow had a 35% infestation of live, feeding larvae.
Pea aphids were also detected in every alfalfa field sampled. Some were already producing nymphs. Unlike last week, no lady beetles or mummified aphids were noted, but an adult green lacewing was collected from the alfalfa canopy.
For more information on Alfalfa Insect Management, please visit: https://www.bookstore.ksre.ksu.edu/pubs/mf809.pdf