Since its detection on these crops in 2013, the sugarcane aphid has become one of the most important pests of grain sorghum and forage sorghums in the southwestern U.S. During the 2014 growing season, it spread over much of the South, and dispersal continues. Dr. Doug Johnson reported on movement of the sugarcane aphid up the Mississippi River Valley in a Kentucky Pest News article posted on July 14, 2015. The map (Figure 1) shows the detected progress as of July 24. It appears that the insect has made it to Kentucky.
Pictures of aphids collected from a Fulton County grain sorghum field (Figure 2) by Ben Rudy, county Extension agent, have been confirmed as sugarcane aphids from a sample sent to the UK Entomology Department.
Aphid colonies were found on some plants in one corner of a field in which grain heads were forming, but the insects were below a damaging level. There was no indication of the insects in other portions of that field nor were any found in another field planted in mid-June.
The aphid, which varies from pale yellow to tan, has dark tips on the antennae, feet, and cornicles (a pair of small tubes that project from the rear of the abdomen). The corn leaf aphid also infests grain sorghum but usually does not cause significant damage. It is important to have suspected sugarcane aphid identifications confirmed. This also will provide a picture of the spread of the insect.
Infestations begin when winged female aphids arrive in fields and deposit live young on the undersides of leaves. As with other aphids, populations can increase rapidly. These sap feeders produce large volumes of sticky, sugary honeydew waste. Honeydew accumulations provide a food source for sooty mold. The aphids will move from leaves to feed on grain heads.
Information on the sugarcane aphid and field sampling protocols is available in The Sugarcane Aphid: A New Pest of Grain and Forage Sorghum.
By Lee Townsend, Extension Entomologist