Right on time with last year’s observations, adult spotted lanternflies (SLF) were found in Pilesgrove (Salem County) NJ. In 2020 adults at the same location were found on July 23 so despite the earlier hatch observed in May, the phenology is right on track.
Adults were not the dominant life stage, mostly fourth instars were observed. Now is a critical time for management efforts as even these young adults will not become reproductive until September. Adults will congregate on trees, feeding in groups to access the phloem. At this time of year they prefer black walnut and tree of heaven and will gradually move towards red maples, willow, river birch, and sycamore. There are other hosts, these are just the ones we have consistently found high numbers of adults on in NJ.
In 2020, adults dispersed in large numbers to commercial vineyards around September 4. I think this dispersal is a combination of depletion of resources (they are literally sucking the sap out of trees) and density. As NJ populations of SLF increase, they are depleting food resources faster. I expect this movement from wooded areas to vineyards will happen earlier this year, likely mid August. There will be a few bugs here and there, but commercial vineyard managers should wait to apply insecticides until you see the larger influx. Across sites, the 10 adults/vine threshold was reached around the same time last year – although some vineyards had much larger numbers per vine – so this is a good threshold to use for now. I will post management recommendations for the adults soon!
