QUESTION
Client requested identification of a large beetle found in her yard.
DIAGNOSIS / RECOMMENDATION
Harpalus pensylvanicus, common name Pennsylvania dingy ground beetle. It is a beneficial insect.
ADDITIONAL INFORMATION
This ground beetle is about 13-16 mm long and is feeds on a lot of different weed species, including foxtails and pigweed and feeds on many pest insects also (ref 1). It breeds in autumn and overwinter in the larval stage. Peak activity density for this species occurs in August and September. (ref 1)
Carabid beetles play a major role in agroecosystems by contributing to the mortality of weed seeds, insects, and slugs. They can consume up to their body weight daily. They eat a wide variety of pest organisms (Ref 1, 2). The adults typically are more active at night. And while they occasionally will come into houses, they do not bother humans (Ref 3). In agriculture, these insects are considered to provide up to 40% protection from crop damage compared to areas where populations are low (Ref 1).
Ground beetles are very important contributors to controlling insects and weeds. Gardeners should welcome these insects into their yards and provide places for them to live. Providing habitat for beneficials such as ground beetles should be part of every gardener’s management plan.
RESOURCE LINKS
1 – https://extension.psu.edu/ground-and-tiger-beetles-coleoptera-carabidae
2 – https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/ENTO/ento-249/ENTO-249.pdf
3 – https://extension.umn.edu/nuisance-insects/ground-beetles
(All resource links live and accessed August 3, 2022)
By: Betsy Brown, Bedford Extension Master Gardener Volunteer; Help Desk Coordinator