The three major arthropod pests of hops in the Northeast are Potato Leafhopper (PLH), Two-spotted Spider Mites (TSSM), and Hop Aphids (HA). This incidence of these pests in hop yards is based on the weather conditions, and we found that the hop aphids preferred cool and moist conditions and populations peaked around the time of harvest through September. For more information about disease, weed, and insect pest populations, check out our six-year study, Organic Hop Variety Trial .
Hop aphids (Phorodon humuli) are small soft-bodied insects that come in both wingless (immature individuals) and winged (adult females) forms, both of which are found on hop plants. Hop aphids are pear shaped and range in color from pale white to a yellowish-green and are found on the underside of the hop leaf. They do not over winter on hops, but rather on a variety of plants in the Prunus genus (Family Rosaceae). Hop aphids over winter as eggs and in early spring the eggs hatch and reproduce asexually for one or two generations before the winged form migrates to hop plants in May.
These small insects have piercing-sucking mouth parts that are used to feed on the hop leaves and cones, and suck the phloem from the plant. This can cause leaves to curl, and turn cones brown and limp. Hop aphids also release a sugary substance called “honey dew”, which allows for the growth of sooty mold fungi on the hop leaves and cones. While leaf feeding can decrease the marketability of the crop, the bigger threat to hop yield and quality is the sooty mold which results in aesthetic cone damage and a decreased cone quality.
It is important to start scouting early in the season and monitor hop aphid populations throughout the season. One way to control hop aphids is the use of natural enemy arthropods. A list of management tactics and natural enemy arthropods can be found in Hop Aphid, Phorodon humuli (Schrank), in Northeastern Hop yards.