A problem for roots

The invasive Japanese beetle (Popillia japonica) is notorious for the damage that it causes both above and below ground.  Above ground, adult beetles can be seen voraciously consuming foliage and flowers.  Below ground, beetle larvae feed so extensively on the roots of grasses that conspicuous dead patches form on the lawn above.  However, not all dead patches of grass should be blamed on Japanese beetles; some may be due to another Asian beetle with a large appetite for roots: the oriental beetle (Anomala orientalis).

An oriental beetle (Anomala orientalis) sitting on a daisy.

Like the Japanese beetle, the oriental beetle was also accidentally introduced to North America from Japan in the early 20th century and has been gradually expanding its range.  In contrast to the Japanese beetle, though, adult oriental beetles are not very destructive (I have seen several but never observed one feeding).

Another brown oriental beetle sitting on, but not eating, a fern.

A particularly interestingly aspect of oriental beetles is that they come in several color variations.  Can you spot the slight differences in the patterns of the two beetles above?  I've put a hint below the next picture, which illustrates a more extreme example of color variation.

The less common, black form of the oriental beetle (Anomala orientalis).

Hint: The biggest difference is on the thorax (the segment between the head and the abdomen).  The first beetle has a solid brown patch, whereas the second beetle has a white line dividing the brown patch.  The patterns of white and brown on the elytra (the wing converings on the top of the abdomen) are also not quite the same.  See even more examples on the Natural Current Events Facebook page.