Belongs within: Melolonthini.
Melolontha is a Eurasian genus of large cockchafers with a deeply incised labrum beneath a subquadrate clypeus, and a basal tooth on the mid and hind tarsal claws.
Fruit destroyers
Published 30 September 2024
I’ve written before about the challenges facing anyone who might attempt a revision of the scarabaeid subfamily Melolonthinae. Key to any such undertaking would be the genus Melolontha, the type genus and thus lynchpin of the whole affair.
Members of the genus Melolontha, commonly known as cockchafers*, are widespread across the Palaearctic and Oriental realms. They are relatively large beetles, growing to about an inch in length. As with other melolonthines, they are typically dull in colouration, though the northern Indian M. virescena exhibits a metallic green pronotum (Li et al. 2010). Characteristic features include a deeply incised labrum, toothed tarsal claws, and a significant posterior extension of the pronotum (Laporte de Castelnau 1840). Over fifty species of Melolontha have been recognised to date, with (as always) more awaiting description.
*A name it took me an embarrassingly long time to realise was funny.
Cockchafers are generalist feeders, happily gorging themselves on a wide range of plant species. Larvae are soil dwellers feeding on roots; adults browse upon leaves. As a result, several species have been regarded as significant agricultural and silvicultural pests, their targets ranging from hardwood and softwood trees to stonefruit to root vegetables to grains. The classical Greek name melolónthe from which the name of the genus is derived may itself be translated as ‘fruit destroyer’. Adults may cause at least temporary defoliation of entire trees but their impact is often minimal compared to that of the larvae destroying root systems. The common cockchafer Melolontha melolontha is more commonly associated with the loss of commercial crops whereas the forest cockchafer M. hippocastani has a more serious impact on forestry. Other species have been reported affecting crops in India (Rana et al. 2022). Widespread pesticide use greatly reduced the impact of cockchafers in many regions in the latter half of the 20th Century, but numbers have rebounded in recent decades.
Part of the reason cockchafers have such a strong impact is their long life cycles, with larvae remaining in the ground (and presumably munching all the while) for some years. In the Czech Republic, populations of Melolontha melolontha followed a three-year cycle whereas M. hippocastani followed a four-year cycle (Švestka 2010). These cycles could extend to four or five years in more northern parts of Europe. Adults typically emerge in late spring, from mid-April to the end of May. Males are typically more mobile than females, swarming around dusk while females remain feeding in trees (Reinecke et al. 2002). Research into methods to control this flight continues apace, as producers seek to shield their crops from the marauding beetles.
Systematics of Melolontha
Melolontha
|--M. aestivaR26
|--M. agricolaL02
|--M. albidiventris Fairmaire 1889F89
|--M. argenteaL02
|--M. arthriticaL02
|--M. candicansF89
|--M. costipennis Fairmaire 1889F89
|--M. cuprascens Blanch. 1871F89
|--M. fuliginosa Fairmaire 1889F89
|--M. fulloR26
|--M. hippocastaniB14 [incl. M. hippocastani var. baicalicaC01]
|--M. horticolaL02
|--M. hybridaF89
|--M. mauritanica Lucas 1846E12
|--M. melolontha (Linnaeus 1758)B14
|--M. pectoralisB14
|--M. piniR26
|--M. rubiginosa Fairmaire 1889F89
|--M. rufocrassa Fairmaire 1889F89
|--M. ruricolaL02
|--M. solstitialisR26
|--M. squamosaL02
|--M. suturalisB35
|--M. umbraculataF89
|--M. villosaR26
`--M. vulgarisL02*Type species of generic name indicated
References
[B35] Boisduval, J. B. 1835. Voyage de Découvertes de l’Astrolabe. Exécuté par ordre du Roi, pendant les années 1826–1827–1828–1829, sous le commandement de M. J. Dumont d’Urville. Faune entomologique de l’océan Pacifique, avec l’illustration des insectes nouveaux recueillis pendant le voyage vol. 2. Coléoptères et autres ordres. J. Tastu: Paris.
[B14] Bouchard, P. (ed.) 2014. The Book of Beetles: A lifesize guide to six hundred of nature’s gems. Ivy Press: Lewes (United Kingdom).
[C01] Csiki, E. 1901. Bogarak [Coleopteren]. In: Horváth, G. (ed.) Zichy Jenő Gróf Harmadik Ázsiai Utazása [Dritte Asiatische Forschungsreise des Grafen Eugen Zichy] vol. 2. Zichy Jenő Gróf Harmadik Ázsiai Utazásának Állattani Eredményei [Zoologische Ergebnisse der Dritten Asiatischen Forschungsreise des Grafen Eugen Zichy] pp. 75–120. Victor Hornyánszky: Budapest, and Karl W. Hierseman: Leipzig.
[E12] Evenhuis, N. L. 2012. Publication and dating of the Exploration Scientifique de l’Algérie: Histoire Naturelle des Animaux Articulés (1846–1849) by Pierre Hippolyte Lucas. Zootaxa 3448: 1–61.
[F89] Fairmaire, L. 1889. Coléoptères de l’intérieur de la Chine. 5e partie. Annales de la Société Entomologique de France, 6e série 9: 5–84.
Laporte de Castelnau, F. 1840. Histoire Naturelle des Insectes Coléoptères vol. 2. P. Duménil: Paris.
[L02] Latreille, P. A. 1802. Histoire Naturelle, générale et particulière des crustacés et des insectes vol. 3. Familles naturelles des genres. F. Dufart: Paris.
Li, C.-L., P.-S. Yang & C.-C. Wang. 2010. Revision of the Melolontha guttigera group (Coleoptera: Scarabaeidae) with a key and an annotated checklist of the East and South-East Asian Melolontha groups. Annals of the Entomological Society of America 103 (3): 341–359.
Rana, A., R. S. Chandel & K. S. Verma. 2022. Morphological description and identification of Melolontha cuprescens, Melolontha furcicauda and Melolontha indica (Coleoptera: Scarabaeidae): serious root feeding and defoliating pests in India. Phytoparasitica 50: 281–305.
Reinecke, A., J. Ruther, T. Tolasch, W. Francke & M. Hilker. 2002. Alcoholism in cockchafers: orientation of male Melolontha melolontha towards green leaf alcohols. Naturwissenschaften 89: 265–269.
[R26] Risso, A. 1826. Histoire naturelle des principales productions de l’Europe méridionale et particulièrement de celles des environs de Nice et des Alpes maritimes vol. 5. F.-G. Levrault: Paris.
Švestka, M. 2010. Changes in the abundance of Melolontha hippocastani Fabr. and Melolontha melolontha (L.) (Coleoptera: Scarabaeidae) in the Czech Republic in the period 2003–2009. Journal of Forest Science 56 (9): 417–428.