- Scientific Name: Schizaphis graminum (Rondani) with several biotypes. [Phylum Arthropoda: Class Insecta: Order Homoptera: Family Aphidae]
- Common Names: greenbug, greenbug aphid
- Climatic Zone: temporate
- Geographic Distribution: Reported to have damaged turfgrass from Kansas to New York and south into Kentucky and Maryland; worldwide pest of cereal grains in Europe, Africa, and North America.
- Damaging Stage: adults and nymphs
- Hosts: Different biotypes prefer wheat, sorghum, oats and over 60 members of the grass family; prefers Kentucky bluegrass but will survive and reproduce on Chewings fescue and tall fescue when these have no endophytes.
- Damage Symptoms: Individuals suck plant juices which rob the plant of nutrients and water. However, this aphid has a toxic agent in its saliva which causes the leaf tissue around the feeding site to turn yellow and then burnt-orange. Injury usually begins in shaded areas under trees or next to buildings, often along the north and east sides. This damage may then spread towards sunny areas with the general turf color changing from green to yellow to brown. Damage begins in June and may continue until a killing frosts occurs. This pests seems to appreciate hot dry conditions as rainy periods reduce population outbreaks. Severe damage is most evident in November but may also show up from late July through September.
- Description of Stages: Typically, aphids have complicated life cycles in which the females give live birth to nymphs asexually (ovoviviparous, parthenogenesis) until late fall. At this time, sexual forms are produced and overwintering eggs are laid. Several other species of aphids may be found on turfgrasses, but most of these are dark in color.
Eggs: The eggs are elongate oval, about 0.8mm long, and are green when first attached to grass blades. They turn a shiny black in a couple of days.
Nymphs: These look like adults except they are smaller. The pear-shaped body is light green and usually has a darker green stripe down the back. The tips of the legs, antennae and cornicles (the tail-pipe like structures on the abdomen) are black. Nymphs destined to become winged forms have obvious wing pads in the last instar.
Adults: Adults are about 2mm long and have the same green color of the nymphs as well as black markings. Winged forms usually appear when whenever crowding occurs, often after considerable damage has occurred. Winged adults are usually darker green and have the wing veins marked with black.
- Life Cycle and Habits:
Greenbugs were suspected to migrate into turfgrass from small grain producing fields in the south and west. However, eggs of some of the biotypes have been found which can overwinter in northern climates and nymphs have been found in northern turfgrasses too early in the spring to have been blown in. Also, certain lawns will be infested year after year while adjacent lawns are not attacked. All aphids which hatch in the spring are females which reproduce asexually (parthenogenesis) by giving birth to first instar nymphs (ovoviviparity). In cool weather, these nymphs may take two weeks or more to mature but as summer temperatures rise, only 7-10 days are needed. Thus, populations can literally explode in a few weeks as mature females may produce two to three nymphs per day. Greenbugs seem to prefer the shade and buildup populations in the shade of trees, buildings and fences. Though greenbugs do best in the shade, they reproduce most rapidly in warm, dry weather. As daylight periods decrease in the fall, nymphs are produced which grow into winged sexual forms which can fly to new areas. Apparently these forms seek out suitable places to lay overwintering eggs. Greenbugs produce less honeydew than most of their relatives but enough is often present to attract ants, bees and other sugar seeking insects.
- Control Approaches: Many natural controls normally keep this pest in check but these may be missing in turfgrass habitats. Some populations of this pest may also be resistant to organophosphate insecticides such as dursban and diazinon.
Natural Control - Allow Natural Control Agents Attack Greenbugs - Lady beetles, lacewings and parasitic wasps often seek out the greenbugs and effectively reduce populations if preventive insecticide sprays used to control chinch bugs, sod webworms and cutworms have not been over used.
Cultural Control - Use Resistant Turfgrasses - Perennial ryegrass, zoysiagrass and bermudagrass are not attacked. New research indicates that endophyte infected turfgrasses are generally resistant to greenbugs. Kentucky bluegrass clones which have been identified as being resistant to two greenbug biotypes are: Kenblue 46, A-34 (GB-3), Wabash 21, Delta 20 and Cougar 6. Others are being identified so contact seed source companies for new releases. Is a lawn has been so severely damaged by greenbugs as to require renovation, consider using a resistant turf variety.
Chemical Control - Applications of Pesticides - Greenbugs are relatively easy to control with contact and systemic insecticides applied to active populations. However, some biotypes appear to have some resistance to organophosphate insecticides. If this resistance has been identified locally, application of carbamates, pyrethroids, or a neonicotinoid may be useful.
Greenbugs are most commonly detected by looking for the yellow-orange discoloration of turf around trees and next to buildings. By looking closely at this turf, the aphids can be seen lined up along the upper surface of leaf blades. Color blind individuals may do better by taking an insect sweep net and using it in the area. The darker aphids readily show up next to the white cloth of the net. Sweep netting will also help detect the presence of lady beetles and lacewings.