Management Updates: May 5, 2026
Prolonged Emergence of Annual Bluegrass Weevil Adults
The April weather certainly made it challenging to pinpoint the exact peak of Annual Bluegrass Weevil (ABW) activity. The weather overall was relatively cool with short warm-up spikes from which most of the GDD accumulation occurred. Surprisingly, GDD accumulation to date in CT and Western Massachusetts, which now stands at about 200- 250 GDDs, is very similar to previous years. However, plant phenological indicators are lagging, probably because of low night temperatures. Forsythia was half green/half gold last week and still remains so at many locations. Easten Massachusetts and coastal sites are about a week behind in terms of GDD accumulation (up to 75 GDDs). Forsythia is still in full bloom at these locations.
We observed ABW on short-cut grass in mid-April; numbers were increasing until the cold spell and plateaued after that. The adults seem to not be active when the cold spells occur, but it is not clear how their physiology and egg laying patterns are affected. Therefore, it is hard to precisely predict accurate timing for an adulticide application this season because emergence is likely prolonged and diffused. Recent weather pattern changes and issues with pyrethroid resistance in ABW emphasize the relevance of recommendations to focus on managing larvae. The approach targeting larvae offers a wider “window” for applications and a more diverse range of available effective options/larvicides.
The alternative to adulticides is an “early” larvicide application, which targets young larvae feeding inside of the stem and, if effective, prevents damage. Two insecticides are proven to be effective if applied shortly after the peak of adult activity (within about 2 weeks): novaluron (SupradoTM), and isocycloseram (AtexzoTM). Novaluron is a chitin synthesis inhibitor [insect growth regulator (IGR) class]. This active ingredient is mostly effective against eggs and young larvae but demonstrates great efficacy if applied starting from adult peak until about 2 weeks after. Isocycloseram (AtexzoTM) became available this year for turf use in Massachusetts and is effective if applied targeting adult and first instar larvae (within 1-2 weeks after adulticide application, ~200 GDDs, Forsythia full green).
Later larvicide applications target larvae coming out of the plant to start feeding on crowns in the soil. The timing for this application is when larvae reach about 2.5 instars, ~300-400 GDDs, and Rhododendron is in full bloom. Damage is rarely very obvious at this stage. The larval densities can be easily estimated, and many active ingredients are effective (cyantraniliprole, spinosad, indoxacarb).
Monitoring insect population numbers is crucial before making any application. Recently we have observed reduced ABW densities in the region, so it is important to confirm that the presence and abundance of ABWs warrants insecticide application. ABW abundance can be monitored by vacuum samples, soap flushes, or simply checking clippings collected in mower baskets
Other Insect Pests
Chinch bug adults are active, but no nymphs are present yet. The number of adults are declining. This year we have not observed high numbers of chinch bugs. Spring conditions have been relatively dry, which is favorable for chinch bugs, however, it has also been relatively cool, which might delay the life cycle.
This week we noticed adult flight of the common cranefly (Tipula oleracea) (Figure 1). This species is invasive and damaging to turfgrass, but harmless for pets and humans. They are among two common invasive species, the other being European craneflies, that can be damaging to turfgrass. The two species look very similar but differ in life cycle. At this time of the year, only adults of the common cranefly fly. Both species prefer wet conditions and have not been abundant and damaging in recent years.
Submitted by: Dr. Olga Kostromytska, Extension Assistant Professor, UMass Stockbridge School of Agriculture