Agrilus granulatus populi

Agrilus granulatus populi is often confused with A. quadriguttatus in collections. It can be distinguished from A. quadriguttatus by the following characters: denser pubescence on the lower face that obscures the surface (less dense in A. quadriguttatus); pronotum with lateral margins strongly sinuate at the base and a distinct median channel with pubescent lateral depressions (evenly rounded lateral margins, less distinct median channel, and scarcely pubescent lateral depressions in A. quadriguttatus); and elytra less gradually narrowed posteriorly with tips less acutely rounded, less coarsely serrulate, and with more distinct pubescent spots (more gradually narrowed with more acutely rounded, more coarsely serrulate tips and less distinct pubescent spots in A. quadriguttatus). A. quadriguttatus is associated with willow (Salix spp.) rather than poplar.

Associated with cottonwood and poplar trees (Populus spp.), including native eastern cottonwoods (P. deltoides) and introduced Lombardy poplars (P. nigra var. 'Italica'). Beetles are found on branches of host plants, especially recently dead ones exhibiting branch dieback. In drought-stressed areas with abundant branch dieback, populations can occur in high numbers.

North America; specifically the United States east of the Rocky Mountains for the nominate subspecies A. g. granulatus. The broader species A. granulatus has a wider distribution across North America with multiple subspecies.

Adults emerge during mid- to late spring. In Oklahoma, adults have been observed in June.

Larvae feed within dead or dying wood of Populus species. Adults likely feed on foliage or bark of host plants, though this is not explicitly documented in the source material.

• Populus deltoides - Larval hostNative eastern cottonwood
• Populus nigra var. 'Italica' - Larval hostIntroduced Lombardy poplar

Eggs are laid on bark of freshly killed or declining wood. Larvae develop as wood-borers, creating tunnels filled with fine sawdust-like frass packed behind them as they feed. Larval development and pupation occur within the wood, with adults emerging through exit holes. The complete life cycle likely spans one to multiple years depending on conditions.

Adults are often found hanging on branches of host plants and will fall when branches are tapped—a behavior exploited by collectors using beating sheets. Some individuals can move quickly when disturbed, especially in heat.

As a primary wood-borer in dead and dying branches of Populus, this beetle contributes to nutrient cycling and wood decomposition in riparian and other poplar-dominated ecosystems. It may serve as prey for specialist predators such as the crabronid wasp Cerceris fumipennis.

Collected by entomologists for scientific study and by beetle enthusiasts. May be of minor importance in urban settings where Lombardy poplars are planted as ornamentals. The species has been used as an example in educational materials about wood-boring beetle collecting techniques.

• Agrilus quadriguttatusFrequently confused in collections; distinguished by host association (willow vs. poplar) and morphological characters of pubescence density, pronotal shape, and elytral form
• Poecilonota cyanipesAnother poplar-associated jewel beetle; distinguished by coppery color, elongate reddish elytral apices, and non-angulate pronotal sides

• wood-boring beetle
• jewel beetle
• Populus
• cottonwood
• primary wood-borer
• riparian
• beating sheet target

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