From deadly “kissing bugs” to spiders with 10-foot webs, there are some insects Delaware agriculture officials think we should be on the lookout for — not only during creepy, crawly season but year-round.
Box tree moths
A recently discovered invasive species in Delaware is the box tree moth. Originally from Asia, they start out as a caterpillars, then adults turn into white moths with brown-edged wings.
According to the Delaware Department of Agriculture, the state’s first such moth was discovered in Kent County in July 2024. As of last month, they have also moved into New Castle County.
“Since it’s only been in the mid-Atlantic since last year, we don’t know a whole lot about how its behavior is going to be for our climate and environmental conditions,” said Dr. Brian Kunkel, a pest management specialist for the University of Delaware.
It is believed that the moths have two generations each year. They begin feeding in the spring, but it is not yet known exactly when.
“We don’t know when it stops feeding in the fall or when it starts in the spring. Those are two critical pieces of information we’d like to have — and that’s what we’re working on here at the university,” Dr. Kunkel explained.
Box tree moths like to lay their eggs in boxwoods where hatched caterpillars can feed on interior portions of the plants. However, this can be problematic, since it won’t be immediately apparent that the trees are being eaten until the damage is done.
This destruction can look like browning, chewed up or missing leaves.
To lessen the effect of these moths, the Department of Agriculture recommends monitoring boxwoods regularly, including checking the interiors of the plants.
Spotted lanternflies
Regarding this species, Dr. Kunkel wanted to get one thing clear: They do not kill trees.
“There has been no evidence that says spotted lanternflies kill trees. It makes them look ugly, and they’ll coat them in honeydew — which sooty mold will grow on, but sooty mold doesn’t kill trees either,” he said.
What the flies do kill are hops plants and grapevines. And, though this vegetation is not the state’s primary form of agriculture, Dr. Kunkel said environmental officials don’t want this species to spread to areas where it can cause harm to people’s livelihoods.
Therefore, everyone is encouraged to squish the bugs, which arrived here first in northern Delaware, via southeast Pennsylvania. They have come and gone in areas of New Castle County and recently were spotted in Sussex, where they are more widespread.
“It’s just now getting into the area, so it’s spreading out,” Dr. Kunkel explained. “The arthropods and animals down there that would eat them are just now finding out that they’re edible. So, they’re not (yet) keeping those populations suppressed as much as we’d like.”
Kissing bugs
Kissing bugs are native to Delaware, though they were only identified as being in the state in 2019, by the Centers for Disease Control and Prevention.
There is only one species of the bug here, called Triatoma sanguisuga.
Unlike the moths and flies above, these insects feed on the blood of animals and humans. They were given their name because it was once thought that they mostly bit faces and mouths, but it is now known that any part of the body is susceptible.
Dr. Jennifer K. Peterson, a medical entomologist for the University of Delaware, has been studying kissing bugs since 2010. She was first inspired to do so after watching a documentary about Chagas’ disease, which can develop from the Trypanosoma cruzi parasite that some of these bugs can carry.
When the insect bites a human, it can transplant the parasite through its excrement.
Chagas’ disease starts out with flu-like symptoms but can cause serious heart and gastrointestinal issues down the line.
The first kissing bug infected with T. cruzi was reported in New Castle County in July 2023. And, though these insects have been found in all three Delaware counties, Dr. Peterson said they are not usually located north of Interstate 95.
“That’s where the geology of the landscape goes from coastal plain to Piedmont (or hilly). That’s also like a transitional area where there are changes in altitude and all sorts of things,” she continued.
“I can’t say if it’s that or if it’s just an increase in human development because they do tend to be in forested areas.”
Dr. Peterson stressed the importance of not squishing kissing bugs, due to the parasite residing in their stomachs. Instead, put them in plastic bags and freeze them, flush them down the toilet or send them to the university for testing. Email kissingbugsde@gmail.com for details.
Joro spiders
Though Joro spiders are not yet residing in Delaware, Dr. Kunkel said it’s only a matter of time. He described the state as “completely surrounded” since the arachnids have been spotted west of Philadelphia, in Baltimore and in Salisbury, Maryland.
These spiders, including their legs, can be 4 inches in diameter — about the size of a softball. And their webs can be very large, reaching diameters of 10 feet.
Hailing from northern Asia, Joros were described by Dr. Kunkel as more of a nuisance than a threat to humans’ or animals’ safety. He added that it’s typically difficult for their fangs to puncture human skin.
When they do arrive here, it is likely they’ll be here to stay because they multiply very quickly and would be able to survive winters in this area.
Dr. Kunkel recalled that a colleague in Georgia counted about 150 Joro spiders in his yard in the spring. By the fall, he had counted over 130 more.
Usually, they are noticed in late September through October, when they are fully grown.
“But the nice thing is, it’s perfectly timed for Halloween,” Dr. Kunkel joked.
Plus, with the species’ colors of blue and gold, maybe it could become a new state symbol.
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