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Glischrochilus quadrisignatus (say).jpg
Four-spotted sap beetle, Glischrochilus quadrisignatus, from North America
Scientific classification e
Kingdom: Animalia
Clade: Euarthropoda
Class: Insecta
Order: Coleoptera
Family: Nitidulidae
Subfamily: Cryptarchinae
Tribe: Cryptarchini
Genus: Glischrochilus
Reitter, 1873

See text.


Glisrochilus Auctt. (Lapsus calami)

Glischrochilus (sometimes misspelled as Glisrochilus)[note 1] is a genus of sap-feeding and predatory beetles under the family Nitidulidae, subfamily Cryptarchinae.[1] Most members of this genus are commonly known as picnic beetles or beer bugs.


Glischrochilus are oblong shiny black beetles with attractive yellow, red, or orange markings on their elytra. Their elytra are short and expose the upper surface of their last abdominal segment(s), a good way to distinguish them from the superficially similar but generally larger Megalodacne beetles. They are so similar that some species of Glischrochilus were once classified along with Megalodacne under the now reclassified genus Ips.[2]

Like other nitulidid beetles, adult Glischrochilus can be distinguished from other kinds of sap-feeding beetles by their characteristic 11-segmented antennae that end with a 3-segmented ball-like club. Glischrochilus are among the largest of the nitulidid beetles, but they are still generally smaller in comparison to other beetles, averaging at only 5 millimetres (0.20 in) in length, with larger specimens at 12 mm (0.47 in) long.[3]

Glischrochilus eggs are sausage-shaped and milky white. Eggs are laid during spring near decaying plant matter. Larvae are about 6.4 mm (0.25 in) long and feed for three weeks on fermenting juices and then pupate. It takes a little over a month for picnic beetles to develop from egg to adult and only one generation is produced each year.[4][5]


European bark beetle predators, Glischrochilus quadripunctatus, are predators of the larvae of wood-boring insects, particularly bark beetles.[6]

Glischrochilus beetles from the subgenus Librodor, consisting the majority of species in the genus, feed on exuding sap from injured trees and decaying vegetable or fungal matter. They are also attracted to ripening fruits, as well as beer, vinegar, wine, fruit juice and fermenting beverages. They frequently drown as they feed, rendering these liquids unsuitable for consumption. They congregate in large numbers when such beverages are present, often ruining picnics and outdoor gatherings like barbecues, earning them their common names of 'picnic beetles', 'picnic bugs', or 'beer bugs'. Researchers who wish to attract the bugs use bait that contains beer, molasses, vinegar, pineapple and other ingredients.[5]

Glischrochilus beetles from the subgenus Glischrochilus on the other hand are facultative and obligatory predators of soft invertebrates (including insect larvae) living under tree barks.[6][7]

Species from both subgenera are found in North America and Eurasia.[8]

Glischrochilus are also known to be involved in the transmission of the plant pathogenic fungi Ceratocystis and Fusarium.[7] They are also considered pests of certain fruit and vegetable crops like strawberries, corn, tomatoes, apricot, muskmelons, raspberries, and peaches. They normally only become a problem when fruits are damaged or are overripe and beginning to ferment.[4][9] They are difficult to control as they are primarily attracted to the odor of food. Methods of control include scent baits and removing damaged or overripe fruits.[10]


Glischrochilus belongs to the subfamily Cryptarchinae under the tribe Cryptarchini. It contains two subgenera, Glischrochilus and Librodor.[11]

They were first described by the German entomologist Edmund Reitter in 1873. The name Glischrochilus is derived from the Greek words glischro (sticky) and χείλος (cheílos, lip).[1]

List of species[edit]

The following list may be incomplete or inaccurate:[12][13][14][15]


  1. ^ a b Tony DiTerlizzi (10 January 2007). "Genus Glischrochilus". Retrieved 20 January 2011. 
  2. ^ Bob Ikin; Alison Roach; David Rees; Jonathan Banks (March 1999). "Pest risk analysis of a proposal for the importation of feed grain maize (Zea mays) from the USA". Stored Grain Research Laboratory, CSIRO Entomology, Canberra; AQIS, Canberra. Retrieved 20 January 2011. 
  3. ^ Valerie J. Cervenka; Thomas C. Skalbeck; John F. Kyhl; Darren C. Blackford; Jennifer J. Juzwik; Steven J. Seybold (2001). How to identify common nitidulid beetles associated with oak wilt mats in Minnesota (PDF). North Central Research Station, U.S. Department of Agriculture. 
  4. ^ a b Jeffrey Hahn (September 1999). "Sap Beetles in Home Gardens". University of Minnesota Extension. 
  5. ^ a b William F. Lyon; Roger N. Williams (1991). "Sap beetles". Ohio State University. Retrieved 20 January 2011. 
  6. ^ a b John L. Capinera, ed. (2008). Encyclopedia of Entomology. 1 (2nd ed.). Springer. pp. 3248, 3412, 1511, 3871. ISBN 978-1-4020-6242-1. 
  7. ^ a b A. G. Kirejtshuk. "Essay on the family Nitidulidae from the monograph". Zoological Institute of the Russian Academy of Sciences. Retrieved 20 January 2011. 
  8. ^ "Genus: Glischrochilus". Global Biodiversity Information Facility. Retrieved 20 January 2011. 
  9. ^ "Picnic Beetle Glischrochilus quadrisignatus". Illinois Natural History Survey. 
  10. ^ Maurice Ogutu; James Schuster. "Picnic Beetles - Sweet Corn". University of Illinois Extension. Retrieved January 21, 2011. 
  11. ^ J. McNamara. "Family Nitidulidae (sap beetles)" (PDF). Canadian National Collection of Insects, Arachnids and Nematodes. Retrieved 20 January 2011. 
  12. ^ Michele B. Price; Theresa Cira (April 2, 2008). "Cryptarchinae: Glischrochilus Page". University of Wisconsin–Madison. Retrieved 20 January 2011. 
  13. ^ A. G. Kirejtshuk. "Sap beetles of the genus Glischrochilus (Nitidulidae: tribe Cryptarchini) - atlas of beetles of Russia". Zoological Institute of the Russian Academy of Sciences. Retrieved 20 January 2011. 
  14. ^ Roy Danielsson (February 20, 2009). "Coleoptera: Erotylidae present in the Entomological Museum of Lund University". Entomological Museum of Lund University, Sweden. Retrieved 20 January 2011. [permanent dead link]
  15. ^ "Glischrochilus (Genus)". ZipCode Zoo. April 26, 2009. Retrieved 20 January 2011. 
  16. ^ "Sap Beetles". Utah State University Extension Service. Archived from the original on May 23, 2017. Retrieved May 22, 2017. 
  17. ^ a b c "Glischrochilus". GBIF. Retrieved 2018-05-04. 


1 For example, Finsberg, T. A. C. 2009. Insektsliv och vegetation vid brandfältet på Stora Fjället ett år efter, pp.13

External links[edit]