The College of Computer, Mathematical, and Natural Sciences hosted a Reddit Ask-Me-Anything spotlighting research on the biology and management of invasive insect pests.
University of Maryland Entomology Professor Emeritus Michael Raupp and Professor Paula Shrewsbury participated in an Ask-Me-Anything (AMA) user-led discussion on Reddit to answer questions about the biology and management of invasive insect pests on July 15, 2026.
Raupp and Shrewsburg have a combined experience of six decades studying a stream of egregious insect invaders from around the world. They develop, implement and evaluate sustainable pest management practices—including landscape modification, biological control and non-chemical alternatives. Using a variety of outreach platforms, they help private citizens, horticultural practitioners, agencies and institutions manage invasives in economic and environmentally responsible ways.
This Reddit AMA has been edited for length and clarity.
Have you found that your research often goes beyond insect ecology, such as tree diversity, soil composition, etc.? Do you have other interests in the biology field that intersect with your insect research?
We are applied ecologists and work closely with scientists and practitioners in a wide variety of fields beyond entomology to solve problems associated with urban forests. Our teams include pathologists, agronomists, horticulturalists, urban foresters, arborists, economists, and many others. This work includes understanding and mitigating threats to urban forests, including the importation of invasive species, loss of plant and animal diversity, use of nonnative plants, climate change, and effects of anthropogenic inputs like fertilizers and pesticides on pests and beneficial insects. We have written a nice summary of some of these threats. We are also enthusiastically engaged in scientific outreach to businesses and the general public through print and non-print media.
What have you heard or learned about the black fig fly? It’s decimating figs in California, and it’s so new that nothing is listed to control it.
This one is a bit out of our wheelhouse, but following its detection in California in 2021, the black fig fly rapidly expanded its foothold in California and increased losses to commercial and non-commercial fig growers. As with many insect pests that invade California, such as the cottony cushion scale and ash whitefly, clever scientists have been able to reunite beneficial insects from an invader's native realm with the pest in its new home and achieve remarkable reductions in losses associated with these pests.
We are still early in the invasion, and unfortunately, it takes time to develop sustainable approaches like biological control to help mitigate this pest. As you mentioned, the guidance from the California Department of Agriculture and the University of California hinges on using netting to prevent flies from reaching the fruit and reducing local populations by destroying fallen fruit to interrupt the black fig fly life cycle. At present, entomologists are exploring additional biological approaches like traps and chemicals to expand the arsenal of tools to manage BFF.
I started seeing hammerhead worms in Houston in 2022. What should I do if I see them?
Sorry to hear about the hammerheads. They produce a potent toxin, and it is important to wear gloves if you decide to handle them. Please keep pets away from them if possible. They tend to break if handled, and the two parts can regenerate, so picking them up is dicey. You can treat them in the soil with a spray of vinegar or by putting salt on them. Please don’t broadcast vinegar or salt on the landscape, as it will harm plants. If you place them in a bag, you can spray or douse them there and place the bag in full sun or a freezer to destroy them. You can learn more about this via Penn State or on my blog.
Is it possible to stop the spread of the Oak processionary moth into Northern Europe? Or could we expect its predators to eventually spread north as well and limit the problem?
The processionary moth is not only a pest of trees; it's also a health issue because the urticating (stinging) hairs of the caterpillars result in skin irritations and respiratory distress. For many years, the processionary moth has invaded central and southern Europe. It has been occasionally found as far north as Sweden, so the likelihood that the climate of Denmark will support processionary moths is high. Once an invasive species becomes established and widespread, the possibility of eradication and limiting the spread becomes extremely difficult.
So, to answer your question, it is unlikely that we can stop this movement northward. Further complicating the spread are the effects of a warming climate, which allows invasive species once constrained by cooler temperatures to expand their range northward. Drought can create stress on trees that reduces their ability to defend themselves from insect pests.
There is some good news here. A complex of predators attacks and kills a variety of leaf-eating caterpillars, including the processionary moth. Ground beetles native to much of Europe, such as Calosoma sycophanta, are important predators of the processionary moth. So, with any luck, as the processionary moth expands to countries such as Denmark, its complex of natural enemies will follow and help reduce populations.
Has the campaign to have the public kill spotted lanternflies on sight had an appreciable effect on their spread, or is that even something we can measure?
In the early stages of the infestation in Burkes County, Pennsylvania, the good citizens of Pennsylvania killed more than a million spotted lanternflies. Since then, the lanternfly has spread more than 650 miles from its original point of origin. It is now found in 18 states and the District of Columbia. We get that people want to do something positive to stop the spread and the nuisance caused by spotted lanternflies. However, we simply don't know what effect activities such as scraping egg masses or stomping on lanternflies have on the larger population dynamics of lanternflies. That said, in vineyards, we do know that destruction of egg masses and removal of the invasive tree of heaven (an invasive tree that is one of the major hosts of spotted lanternflies) are tactics to help reduce populations.
Contrary to early fears about spotted lanternflies, we now have more than a thousand observations of predators and parasites putting a beatdown on spotted lanternflies. We also know that two naturally occurring bacteria (Beauveria and Batkoa) have been responsible for collapsing local populations of spotted lanternflies in Pennsylvania. For additional information on SLF and its management, go here.
In areas where spotted lanternfly populations have been established for several years, populations have begun to decline, likely due to natural enemies and better management practices.
For those of us with stink bug infestations, I've found that a reflector lamp clamped onto the side of a 5-gallon pail filled halfway with water will eliminate many of the critters.
Thanks for sharing your clever idea! There are commercially available light-driven traps for the brown marmorated stink bug (BMSB). BMSB was an invasive species that many in the mid-Atlantic region are familiar with. Like a tsunami, the invasion continues on an expanding front to the west and has already reached the West Coast. It is now found in 47 states and Washington, D.C., as well as four Canadian provinces.
Once again, we can thank a complex of indigenous and imported predators and parasitoids that have dramatically reduced stink bug populations in many parts of the invaded range. To learn a bit more about managing BMSB in your home, you can check out this video.
If there was one thing you could get the broader public to understand or do related to this topic, what would it be?
Wow, this is a profound question. Although there are many things to take home, we want to help people understand the vital roles that the biodiversity of plants and animals play in making managed and natural landscapes resilient and sustainable in the face of invasive species, global warming, and urbanization.
Why do certain insects give me the ick while others like butterflies or ladybugs seem almost dear to me? Is there something to this beyond social conditioning?
Your concerns are shared with many others, so you're not alone. Pop culture often villainizes insects and spiders, associating them with illness, uncleanliness and danger, while insects like butterflies and lady beetles are considered visually appealing and beneficial. Most people don't understand the important role arthropods like spiders and wasps play in controlling pests in gardens and natural habitats. Increasing knowledge of these insects may help reduce the "ick" response.
In discussions with many people with phobias, they believe the long legs, hairiness and "creepy" movement make certain insects and spiders very scary. Social conditioning certainly can be a part of this. Oftentimes, youngsters are highly interested in playing with and learning about arthropods, but interacting with peers or elders can introduce negative associations/feelings about insects.
