Fall 2014 Interesting Finds: Beetles (Order: Coleoptera)

Beetles (Order: Coleoptera)

Beetles are the largest group in the animal kingdom. 25% of all known animal species are beetles. 400,000 species have been described so far and many scientists believe that there are as many as 1 million beetle species on Earth. Beetles have inhabited our planet for more than 300 million years which means they were around even before the dinosaurs.

Among the 211 beetle species caught in the Fall 2014 School Malaise Trap Program were quite a few pest beetle species, especially those of the leaf beetle family (Chrysomelidae), such as the strawberry rootworm (Paria fragariae). Beetles from this family are known to feed on particular fruits and vegetables as you can easily tell from their common name.

Warty leaf beetle (Exema canadensis)
Warty leaf beetle (Exema canadensis)

It is not uncommon for larvae in several subfamilies of Chrysomelidae to use their own excrement to form protective shields or coverings, but the warty leaf beetle’s larvae in the subfamily Cryptocephalinae take this habit to the extreme. The warty leaf beetle’s eggs hatch underneath a fecal blanket which their mother has provided for them and then the larvae proceed to use their own waste to further develop a case which they continue to add to as they grow. You may think that this practice is unpleasant; however, this casing serves a very important function. Warty leaf beetles are able to avoid observation and detection from predators due to the fact that their specialized casing resembles caterpillar frass (caterpillar poop).

https://www.flickr.com/photos/treegrow/14207190032/in/photolist-mYK2Lg-2XHfmK-qhrcXm-nDryCh-ccb66w-p1W9qh-8hyteE-bptdyL
Warty Leaf Beetle

Warty leaf beetle species are typically very host plant-specific and most species primarily use only a single host plant genus or even a single species to feed and live on. Congratulations to Camp Heidelberg for collecting the only species (Exema canadensis) of warty leaf beetle ever obtained during the School Malaise Trap Program.

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