Annual Bluegrass Weevil (ABW)
Despite alternating cool and warm temperatures in the beginning of the ABW season, GDD accumulations have been the highest (as of May 11) of any year since 2019. For example, the recent lowest accumulation for this date, 130 GDD, was recorded in 2020 at the Bloomfield, CT location. In comparison, the current GDD accumulation at the same location is 300 GDD (as of May 11). In Western Massachusetts, accumulations are not far behind (~250-275 GDD). In Eastern Massachusetts and Cape Cod, GDD accumulations are lagging by about a week. That is not surprising, since spring often brings sea breezes to coastal locations, and daytime highs can be 10 to 15 degrees cooler than more inland locations.
ABW development is a little bit behind GDD, but is in accordance with plant phenology this year, and we’ve started seeing 1st instars in our samples. Occasional 2nd instars have been found in the samples taken from the most advanced site (Bloomfield, CT). As of May 14, the average stage for most of the monitored locations is at 1.2-1.6 instar. Dogwood is in full or late bloom, and GDD accumulations are approaching or have reached 300. All of this indicates that it is too late for adulticides at this point, and the focus should be on management of larvae feeding inside of the stem. At this stage only systemic insecticides can reach larvae, therefore anthranilic diamides (chlorantraniliprole, cyantraniliprole, and tetraniliprole) can be effective during this time. Novaluron, an insect growth regulator, is also still effective if applied at this time.
This year has been challenging for managing overwintering adults because of the fluctuating temperatures, and it is continuing to be challenging. Rapid GDD accumulation, which speeds up insect development, combined with frequent heavy rainfall makes scheduling insecticide applications difficult. It is important to avoid spraying if heavy rainfall in forecast, because heavy precipitation (>1”) can compromise efficacy of the active ingredients due to runoff and leaching. ABW are sometimes referred as “semi- aquatic” insects, thus they most likely benefit from wet conditions, similarly to their preferred host, Poa annua.
Billbugs
Billbugs are on the move already, our trap catches have been increasing recently, and we have observed adult billbugs in vacuum samples. It’s about time for adult activity to peak (last week of May) and we are closely monitoring billbug activity. All three species (bluegrass, hunting, and lesser billbugs) have become active already.
Monitoring adult activity is important for two reasons. First, one of the preventive management approaches is to apply adulticides (primarily pyrethroids) during the peak of adult activity. This strategy is not very effective, but might be necessary as a first step under high billbug pressure. Secondly, the adult activity serves as a biofix; an event which can be used to estimate and predict larval activity. For instance, about 2 weeks after adults peak it’s expected that larvae will start feeding inside of the plants, therefore it will be good timing to deploy systemic insecticides (usually neonicotinoids).
Chinch bugs
The first nymphs have appeared in our samples (May 12), however adults are still present and mating. The number of chinch bugs in our samples remains low (compared to the 2024 season) and we do not expect high densities in the first spring generation. Chinch bugs prefer dry and hot conditions. A wet spring is also usually associated with high activity of the naturally occurring entomopathogenic fungus Beauveria bassiana, which is a main factor contributing to natural mortality of chinch bugs, so this spring has presented rather detrimental conditions for them.
White grubs
Recent soil sampling has demonstrated that white grubs are still actively feeding (as of May 13) in the root zone, within the top 2” of soil. If need, they still can be treated. That said, we have not observed severe primary damage (caused by grub feeding) in monitored areas with heavy white grub infestation. It might be because the plentiful rainfall helps the turf to tolerate grub feeding without much damage. However, we have noted secondary damage caused by predators searching for grubs (Fig.1). To avoid this damage, curative grub applications should be considered if an area is prone to predator activity. Alternatively, there is a cultural method, which is application of MilorganiteTM fertilizer, and is commonly cited as helping to repel predators. We have not studied the efficacy of this method and/or its persistence (for how long it remains effective repellent), however... more studies are needed.
Other Turfgrass Insect Pests
Ants are active despite the wet spring, and mounds now can be observed in the short grass, indicating it is now the time for spring neonicotinoid or bait application. Two main considerations are important to keep in mind for ant management: First, ants are effective predators and are beneficial in most turfgrass systems; management most commonly is only required on greens, tees and fairways of golf courses, when mounds become a problem. Second, the long-term control of ants can be only achieved if queen is killed. Application of neonicotinoids and/or contact insecticides (pyrethroids) kills mostly worker ants, while the queen is in the nest below the surface and cannot be reached by active ingredients. Bait application is more likely to result in queen mortality, which leads to colony collapse and long-term suppression.
Non-turfgrass, but a Frequent Pest Encountered Recently
During the last two years, we’ve observed increased occurrence of eastern tent caterpillars in New England landscapes. It is a native early-season defoliator, and creates a nest in branch forks (Fig 2). These nests are used as a shelter and protection from predators, cold and rain in between feeding. Tents are never constructed over the foliage (like webworms do, for example) and so can be an important clue for ID of this species. Caterpillars tend to aggregate, and in addition to defoliation, heavy infestation can be a nuisance.
Submitted by: Dr. Olga Kostromytska