Glischrochilus

Reitter, 1873

picnic beetles, beer bugs

Species Guides

Glischrochilus confluentus
Glischrochilus fasciatus(Picnic Beetle)
Glischrochilus lecontei
Glischrochilus moratus
Glischrochilus obtusus
Glischrochilus quadrisignatus(Four-spotted Sap Beetle)
Glischrochilus sanguinolentus(Bloody Sap Beetle)
Glischrochilus siepmanni
Glischrochilus vittatus

Glischrochilus is a of small beetles in the Nitidulidae, commonly known as picnic beetles or beer . The genus contains two subgenera with divergent feeding strategies: Librodor feed on sap and fermenting plant matter, while Glischrochilus species are of soft . Most species are characterized by black bodies with contrasting yellow, red, or orange elytral markings. The genus is distributed across North America and Eurasia and includes several agricultural pests.

Glischrochilus confluentus by (c) Bill Keim, some rights reserved (CC BY). Used under a CC-BY license.

Glischrochilus lecontei by (c) Matt Bowser, some rights reserved (CC BY), uploaded by Matt Bowser. Used under a CC-BY license.

Glischrochilus fasciatus by Jacy Lucier. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Glischrochilus: //ˌɡlɪs.kroʊˈkaɪ.ləs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Oblong, shiny black beetles with distinctive yellow, red, or orange markings on the . Short elytra expose the upper surface of the last abdominal segments, distinguishing them from the larger, superficially similar Megalodacne. possess 11-segmented ending in a 3-segmented ball-like club, characteristic of Nitidulidae. Body length ranges from approximately 5 to 12 mm, making them among the largest nitidulid beetles.

Images

Habitat

Found in areas with exuding sap from injured trees, decaying vegetable or fungal matter, and fermenting plant materials. Agricultural include corn fields, orchards, and areas with damaged or overripe fruits. in subgenus Librodor are associated with fermenting substrates; species in subgenus Glischrochilus occur under tree bark where soft prey are found.

Distribution

North America and Eurasia. Specific distribution records include Denmark, Norway, Sweden, and Vermont (USA).

Diet

Subgenus Librodor: exuding sap from injured trees, decaying vegetable or fungal matter, ripening fruits, and fermenting beverages including beer, vinegar, wine, and fruit juice. Subgenus Glischrochilus: facultative and obligatory of soft including insect larvae living under tree bark.

Life Cycle

are sausage-shaped, milky white, and laid in spring near decaying plant matter. Larvae feed for approximately three weeks on fermenting juices before pupating. Development from egg to takes slightly over one month. One per year is typical, though three consecutive generations have been observed under greenhouse conditions at 21°C. Adults hibernate; spring-collected individuals have shorter preoviposition periods than autumn-collected beetles. Newly developed adults may remain in soil before emerging.

Behavior

Strongly attracted to fermenting odors from beer, vinegar, wine, fruit juice, and other fermenting beverages. Frequently drown while feeding on liquids. Exhibits when fermenting food sources are present. Congregates in large numbers at outdoor gatherings, earning . Researchers use mixtures containing beer, molasses, vinegar, and pineapple to attract specimens.

Ecological Role

Involved in transmission of plant pathogenic fungi Ceratocystis and Fusarium. Predatory in subgenus Glischrochilus may act as agents for pests such as the European corn borer (Ostrinia nubilalis). Contributes to decay of plant matter and nutrient cycling in agricultural .

Human Relevance

Considered pests of strawberries, corn, tomatoes, apricots, melons, raspberries, and peaches, particularly when fruits are damaged or overripe. Difficult to control due to attraction to food odors; management includes scent baits and removal of damaged or overripe fruits. Common nuisance at outdoor gatherings due to attraction to alcoholic beverages.

Similar Taxa

MegalodacneSuperficially similar black beetles with colored markings, but generally larger with that do not expose the last abdominal segments. Some Glischrochilus were formerly classified with Megalodacne under the Ips.