Tiny white ball floating over the trail at Frick Park, 9 August 2026 (photo by Kate St. John)

10 August 2026

In August in southwestern PA you may notice a tiny white ball floating above the trail, maybe at eye level. If you walk into it you discover the ball is on a thread. It moves horizontally in a light breeze and can raise and lower itself. On closer inspection you can see it’s a white insect.

Planthopper parasite moth (Fulgoraecia exigua) caterpillar dangling on a silk thread (photo by i_will_eat_your_trees on iNaturalist)

The white balls are the caterpillars of the planthopper parasite moth (Fulgoraecia exigua), one of the very few carnivorous moths in North America. The species is not rare but its dietary habits are.

In a super-closeup the tiny caterpillar looks like this.

Closeup of Fulgoraecia exigua caterpillar (photo from Wikimedia Commons)

The adult moth is also tiny with a wingspan from 8-13 mm (0.3 – 0.5 inches).

Female Planthopper parasite moth (photo from Wikimedia)

Since their life cycle is not tied to a host plant, the female lays her eggs on any vegetation where her young will find planthoppers to parasitize. Perhaps she chooses a site where planthopper nymphs are already present.

When her eggs hatch the tiny caterpillars seek an adult planthopper, latch onto it under the wing, and proceed to suck all the juices out of it. Here’s an example of what they’re looking for, the most common green planthopper in PA: Acanalonia conica the green cone-headed planthopper.

Green cone-headed planthopper (Acanalonia conica), photo from Wikimedia

Two closeups from iNaturalist show the caterpillars actively parasitizing green planthoppers.

Planthopper is green and is facing downward.

Fulgoraecia exigua parasitizing a planthopper in Kentucky (photo by gwalters579 on iNaturalist)

Planthopper is facing right.

Fulgoraecia exigua parasitizing a planthopper in PA (photo by ikraynak on iNaturalist)

Eventually this sucking of body fluids kills the planthopper. The caterpillar drops off and, when it’s ready to pupate, it drops from the trees on a silk thread to find a place to make its cocoon.

The shape of the tiny cocoon is unusual. Brandon Woo of The Incorrigible Entomologist likened it to the Sydney Opera House in 2018. That’s what everyone calls it now.

Cocoon of Fulgoraecia exigua (photo )

Eventually the moth emerges and the cycle starts again.

Watch for a tiny white ball on a thread this month. It’s Bug Season!