Meet the Beetles

Maybe a green intruder scurrying down your shirt gave you the heebie-jeebies at a barbecue, or an in-law arched an eyebrow—devastatingly—at the state of your grub-damaged lawn. Perhaps instead of every rose having its thorn, every rose has its chomping insect.

These are just some of the potential effects of this summer’s surging beetle mania. According to entomology Professor Mike Raupp, aka “The Bug Guy,” bumper crops of scarab beetles, including chafers, Japanese beetles, Asiatic garden beetles and May/June beetles, are scuttling in high numbers across our region.

Maryland Today spoke this week to Raupp, who writes the popular “Bug of the Week” blog, about the beetle boom, ranging from practical talk about how to stop the pests, to decidedly philosophical excursions into the meaning of “good” and “bad” in nature.

It’s mostly the moisture.
Last summer was historically soggy, and this one’s been no slouch either, a victim of subtropical-type weather patterns that are at least partly due to climate change, Raupp said. Constantly moist soil enables beetle eggs to absorb water necessary for hatching and makes it easy for beetle larvae, or grubs, to penetrate down into the ground, where they feed on plant roots.

“These guys are all laying their eggs about now, and the little eggs are going to hatch and the larvae are going to say, ‘Oh my God, this is perfect,’” Raupp said. “They're going to burrow down into the ground, the survival is going to be high, they're going to start munching on the roots of plants.”

You think this year’s beetles are bonkers? Just wait until you see what emerges next year if it stays unusually wet, Raupp says: “This is setting us up for the perfect storm for 2020. Oh boy, it’s going to be good.”

Is this a bad thing? It’s all about perspective.
Although higher beetle populations are hardly a crisis, your garden and yard will suffer the consequences, with obvious damage to ornamental trees and shrubs as well as flowering plants and lawns. But it’s not fair to say the bugs are “bad,” Raupp said. “I get this question a lot when I talk to lay audiences, but I don’t think there is bad or good in nature. These are simply organisms that, like all things, take advantage of what Mother Nature presents. … If you’re a rose, I guess this could be an unhappy time, but from the beetles’ standpoint—pretty good.”

Human activity is part of the issue.
The problematic beetles this year are mainly invasive species, brought to the region from overseas in shipments of food, materials or merchandise. “Speaking in general, when new invasives arrive in this country, they leave the baggage behind, so to speak, kind of like flying US Air,” Raupp said. “They leave their natural enemies that evolved to control their populations by using them as food sources behind … and it’s like, welcome to America. Without natural controls, they have a heyday. This is sort of the situation with the Japanese beetle and Oriental beetle and Asiatic garden beetle.”

There are ways to halt their homecoming.
Planting lots of native perennial flowering plants will attract wasp species that feast on beetle grubs, Raupp said. More direct routes of attack include biological controls—tiny organisms that can be applied in your garden that focus only on beetle larvae—and even chemicals. “We have new chemical controls that can be applied to turf grass that are very safe for honeybees, unlike some of the older chemicals which have been banned and were very harmful for pollinators, because they’re taken up through the roots of things like clover and ornamental plants.”

Fireflies: The one shining benefit of all the beetles.
More beetles means more food for another insect far more welcome as a symbol of summer. “Larval fireflies are all maniacal predators that live in the soil and consume insects and other invertebrates including slugs, that are pests in our gardens,” Raupp said. “So when we have these very wet years, I think populations of fireflies, by virtue of the fact that their larvae are surviving better, also experience good years. You know, all these things are related.”