While adult female spongy moths present in North America, in the subspecies Lymantria dispar dispar, cannot fly, several closely related species in Europe and Asia are dubbed the “flighted spongy moth complex,” because their females can fly. Detecting these species before they arrive and establish populations is of the utmost importance and provides the best chance of successful management. A new article in the Journal of Integrated Pest Management details the biology, ecology, and management strategies of two members of this important group of forest defoliators: Lymantria dispar asiatica (adult females shown here inleft two columns) and Lymanria dispar japonica (right column). (Photo by Melody Keena, Ph.D., originally published in Keena et al. 2026, Journal of Integrated Pest Management)

By David Coyle, Ph.D.

David Coyle, Ph.D.

Ah, invasive species. Every time you turn around it seems like there’s another one impacting North America’s agriculture and natural resources. Now, while that’s not entirely true, it sure seems like it sometimes.

One invasive species that’s been here for quite some time, though, is the spongy moth (Lymantria dispar dispar, formerly known as the gypsy moth). This species is firmly established in North America, and countless hours of effort have gone into studying and managing this pest. Spongy moth is somewhat unique in that adult females do not fly. None the less, this species is still capable of spreading widely and causing massive economic ecological damage and impacts.

However, scientists are constantly on the lookout for several other closely related Lymantria species not currently established in North America, of which adult females can indeed fly. Impacts from these species could be even greater due to the females’ flight ability, and a new article in the open-access Journal of Integrated Pest Management highlights two key members of this species group.

The group of five Lymantria taxa—L. albescens, L. umbrosa, L. postalba, and two subspecies of L. dispar: L. dispar asiatica and L. dispar japonica—are termed the “flighted spongy moth complex” and are high on regulatory officials’ “I sure hope we don’t find these in North America” list of pests. Authored by Melody Keena, Ph.D., research entomologist at the USDA Forest Service and colleagues at USFS, Beijing Forestry University, and the Russian Academy of Science, the new profile in JIPM examines the two subspecies L. dispar asiatica and L. dispar japonica in detail.

Caterpillars in the flighted spongy moth complex are voracious defoliators with wide host ranges—they have been observed feeding on over 500 woody and non-woody hosts in their native range! Suffice it to say, if they were to arrive and become established in North America, we’d have a problem.

Several closely related species of Lymantria moths in Europe and Asia are dubbed the “flighted spongy moth complex” because their adult females can fly. Detecting these species before they arrive and establish populations is of the utmost importance and provides the best chance of successful management. A new article in the Journal of Integrated Pest Management details the biology, ecology, and management strategies of two members of this important group of forest defoliators: Lymantria dispar asiatica and Lymanria dispar japonica. Shown here female L. d. asiatica moths gathered and laying eggs on a ship in the far east of Russia. (Photo by Steve Munson, originally published in Keena et al. 2026, Journal of Integrated Pest Management)

Now, from an invasive species perspective, these things are not great (to put it lightly). But from a purely entomological perspective, there are some really interesting biological tidbits about these creatures, all of which are native to Europe and Asia. For instance, some neonates (just emerged larvae) will release a silk strand just after eclosing, and this strand sometimes catches the wind, allowing these larvae to disperse long distances. This behavior is called ballooning (and is also performed by some spider species). Eggs are not tolerant of freezing, and some species have evolved to lay eggs in rock cracks or near the soil (if host trees are nearby) to take advantage of a warmer microclimate in these areas. Rocks and soil hold heat and thus have more moderate temperatures compared to what a standing tree might experience.

Molecular tools have been developed to differentiate Lymantria taxa, as it is critical to know if a newly found Lymantria is from a population that is capable of flight. Why is this critical? Well, because detecting and managing populations of a moth whose adult females cannot fly (e.g., L. d. dispar) is different from detecting and managing a population of a moth whose adult females can fly (e.g., L. d. asiatica). Flying populations will spread farther and faster, obviously, and this presents harder management challenges. Male Lymantria can be trapped using pheromones, though, so at least we’ve got that going for us.

Several closely related species of Lymantria moths in Europe and Asia are dubbed the “flighted spongy moth complex” because their adult females can fly. Detecting these species before they arrive and establish populations is of the utmost importance and provides the best chance of successful management. A new article in the Journal of Integrated Pest Management details the biology, ecology, and management strategies of two members of this important group of forest defoliators: Lymantria dispar asiatica and Lymanria dispar japonica. Shown here are fourth to sixth instar larvae from both subspecies, illustrating the color variation that can be present both within and between populations. Each circle contains larvae from a single female parent. (Photo by Melody Keena, Ph.D., originally published in Keena et al. 2026, Journal of Integrated Pest Management)

As is the case for many invasive species, initial detection is one of the more challenging aspects of a management program. Lymantria are adept hitchhikers, as they will deposit egg masses on nearly anything imaginable. Couple this with the fact that flying adults are attracted to light, and presto! You can have a situation where adult females are attracted to lights at a port, and then they lay egg masses on ships (or cargo on those ships), and then those ships make a trip to another country. Wouldn’t that be unfortunate? Yes, it would, and yes, this really happened; it’s how the U.S. had its first detection of flighted spongy moth back in 1991.

All is not lost, mind you. International collaborations have resulted in a robust detection and management programs for the flighted spongy moth complex, and we possess a lot of knowledge about this group. Detection techniques are constantly being refined and improved, and we’re doing all we can to protect this continent’s natural resources from yet another invasive species.

David Coyle, Ph.D., is an associate professor in the Department of Forestry and Environmental Conservation at Clemson University. Socials: @drdavecoyle. Email: [email protected].