Globular Stink Bug Invasive

This post’s featured creature is Megacopta Cribraria.

August 5, 2010 | Twelvestones, Roswell, GA, USA | ~5mm

Just outside the entrance to my subdivision, there’s a stand of kudzu, Pueraria montana var. lobata, at the border of a city park. If you’re not familiar with kudzu, it’s a major invasive here in the Southeast that pretty much takes over wherever it manages to take root. Many of the volunteer outings with the local nature conservancy are focused on eliminating this invasive from conservancy lands. Here are a few photos of the area to give you an idea.

Covered pine tree

Kudzu towering over trail

While walking past this stand on my way to the park, I noticed several bugs crawling around on some of the large leaves. They piqued my attention, so I took a closer look. I recognized them as a new invasive species themselves that I had read about last year. The adult bugs had gotten attention as they sought shelter from the coming winter in and around homes close to kudzu stands in an area about an hour from me.

Taking a closer look inside the kudzu, you’d see something like this.

You can see all life stages here, including some eggs

Even if you don’t get close enough to see them, you can smell them from dozens of feet away.

I returned later that evening to take some clippings home for some studio shots. The adults are quick to drop and take flight, but I snagged quite a few of those as well.

Most of the egg batches I found were on new growth close to the vine. Here you can see some eggs on a budding leaf. The lighter colored eggs with their caps popped off are empty. The darker ones are on the verge of hatching. The nymph on the left is resting after emergence, and the other one is still working itself out of the egg.

Eggs, hatching | Each egg ~.5mm long

Above, the eggs have been neatly arranged in two rows. That was the common pattern, but there were exceptions. I think the female responsible for the eggs below might have been drunk on kudzu wine.

Another batch of eggs

Note those dark spots at the base of some of the eggs. These are packets of symbiotic gut bacteria provided by the mother that the newborns consume. Apparently the bacteria are host specific, so the ones here will help the bugs digest kudzu specifically.

In the images below, you can see groups of nymphs from various instars  feeding together.

Nymphs feeding near leaf buds

Another group of nymphs feeding

Here’s a closer look.

Nymphs feeding on kudzu vine

Nymph feeding, showing low profile

Fifth instar nymph, with wing buds | ~5mm

The sexes are slightly different. In general, the males are slightly smaller than the females. You have to check the undersides to really tell them apart. The females are lighter on the underside of all abdominal segments, whereas only the first few abdominal segments are lighter in the males. The genitalia are also easily visible. The male’s are roundish and the female’s are more triangular.

Female on left and male on right showing sexual dimorphism

Even in captivity, they weren’t shy.

Two males pursuing a female

Mating

Mating

I saw lots of lacewing eggs, like the one below. I never saw any actual predation though.

That's not a balloon kiddies

Reference:
Occurrence of the Old World bug Megacopta cribraria (Fabricius) (Heteroptera: Plataspidae) in Georgia: a serious home invader and potential legume pest [pdf]