Holotrichia Hope, 1837

Sub family: Melolonthinae / Tribe: Melolonthini / Genus: Holotrichia

Large cylindrical beetles, body length 15-30mm. Body colouration ranging from yellow/tan, brown to dark brown. Antennae 10 segmented, with a 3 segmented club that is enlarged in males. Clypeus usually broadly rounded, sometimes emarginate. Labrum located under clypeus, clearly separated and deeply incised medially, commonly with medially directed setae on each lobe. Pronotal lateral margins usually serrate. Pronotum lacking membraneous anterior margin. Elytra punctate. Foretibia tridentate. Metatibia with 2 apical spurs an a transverse ridge near its mid point. Mesometasternal process is absent. Metasternum setose. Propygidium with lateral sutures. Tarsal claws non-cleft, with a medial tooth.

Many species posess stridulatory ridges along the elytral lateral edge (epipleura).

There are presumed to be more than 240 species within the Holotrichia group. The genus is in much need of an overall revision, and it is in the process of being broken up into smaller genera.  

It is placed within the tribe Melolonthini which share the following features:

Abdominal sternites at least partially fused, sutural lines present between sternites, even when fused. Meso and metatibia with 2 spurs. Tarsal claws usually equal. Antennae 9 or 10 segmented (rarely 8), Antennal lamellae 3-7 segmented. Labrum located below clypeus, distinct. 5th Abdominal sternite and propygidium separated by a suture. Protibia with apical spurs.

Diagnostic resources are scattered and confined to geographic areas.

The name Phyllophaga has been used historically for species of Holotrichia, owing to their closely shared morphology. In practice they are unable to be separated by external morphology.

In the key, Phyllophaga and Holotrichia can be difficult to separate due to the lack of external morphological differences. Origin of a specimen will be the best indicator of separating the between the two: (Oriental region - Holotrichia, Nearctic/Neotropical - Phyllophaga).

Species confirmation generally requires male genitalia examination.

Larvae feed on roots, and can cause sgnificant damage to peanut, potato, sugarcane, maize and peas among others. Adults can also feed on foliage, causing damage to a wide range of fruit and orchard trees.  Some adult beetles may or may not be attracted to lights at night.

The genus Holotrichia is absent from Australia. It is primarily Oriental in distribution, found across India, and through Asia into Japan.

H. bipunctata has spread outside its native range (Phillipines) to Guam, thought to be from movement of the US military.  

PaDIL species page for Holotrichia kiotoensis: http://www.padil.gov.au/pests-and-diseases/pest/main/135632

Holotrichia bipunctata species page (Hawaiian Scarab Website): http://idtools.org/id/beetles/scarab/factsheet.php?name=15191

Dunlap, J.B.,  Jameson, M.L., Engasser, E.L., Skelley, P.E., Redford, A.J. 2015. Scarab and Stag Beetles of Hawaii and the Pacific. USDA APHIS Identification Technology Program (ITP). Fort Collins, CO. http://idtools.org/id/beetles/scarab/

Matsumoto, T. 2010. Four new species of the Holotrichia constricta group (Scarabaeidae, Melolonthinae, Melolonthini) from the Philippines. Elytra, Tokyo, 38(1): 43-52