The scientists examined trees at 26 sites in Raleigh, North Carolina, gathering data on the abundance of the gloomy scale insect, a sap-sucking parasite. ‘We wanted to look at the most important pest species of the most common tree species in urban areas of the southeastern USA,’ said one of the study’s authors, Steve Frank. As well as collecting data on a wide range of ecological variables that could affect gloomy scale populations, the researchers dissected the specimens to count their young.
The results indicated that temperature was the most important predictor of gloomy scale abundance. ‘The warmer it was, the more scale insects we found,’ said Adam Dale, who led the study. ‘At the coolest sites, the females were producing about 20 young, while at the warmest sites, the females were producing around 60. That supports the differences
we saw in scale insect abundance on the trees. Populations at the warmest sites were more than 200 times more abundant than those at the coolest sites.’