Five of America’s Most Wanted Invasive Insects

With sightings of the Asian giant hornet (popularly called the murder hornet in the media) popping up across the northwest, we thought we’d take a look at some of America’s most notorious invasive insects. Unlike Asian giant hornets, these invertebrates already have a strong foothold in the United States and are responsible for millions of dollars in damages every year. It’s all entomologists can do to keep these invasive species in check with biological and chemical controls.  

As you’ll soon read, the entomology field is in desperate need of professionals educated in responsible and effective control measures, including integrated pest management. If a career managing native and invasive insects interests you, apply to one of our entomology and nematology programs. You may one day help prevent an invasive species from making this list.  

1. Africanized Honey Bees 

The Africanized honey bee, sometimes referred to as the killer bee in the media, may be the most well-known entry on this list. Native to sub-Saharan Africa, African honey bees were first brought to Brazil in 1956 by Dr. Warwick Kerr. He believed that through selective breeding, African honey bees could be a more viable option for Brazilian beekeepers than underperforming European bee races, which were struggling in the country’s tropical/subtropical climate. Murphy’s law intervened and the bees escaped, beginning their spread throughout the Americas. Today, these bees are actually the result of African bee hybridization with European honey bees.  

Since first being spotted in Texas in 1990, Africanized honey bees have slowly spread throughout the southern United States. More defensive than western honey bees, Africanized bees have been known to chase a person for a quarter of a mile, which means they can pose a specific threat to those who are not able to quickly seek shelter, such as the elderly, young children or caged animals.  

2. Emerald Ash Borer 

Native to Asia, the emerald ash borer likely found its way to the United States hidden in ash wood used to stabilize cargo ships or crate consumer products. Since being discovered in Michigan in 2002, this aptly named insect has destroyed tens of millions of ash trees across 35 states and the District of Columbia. The process begins when an emerald ash borer deposits its eggs in the bark of an ash tree. Hatched larvae create and feed in curved galleries in the phloem, an inner layer essential for transporting nutrients throughout trees. Nutrient-starved ash trees lose their branches and die within just three to four years of being infested.  

According to the United States Department of Agriculture (USDA), all 16 species of ash trees found in the United States are at risk for emerald ash borer infestation. A domestic quarantine to limit the spread of the insect is currently in effect but proving ineffective. The USDA is instead turning to biological controls, such as stingless wasps that prey on emerald ash borer brood. Emerald ash borers have yet to be spotted in Florida, and it may be the efforts of pest management professionals that are keeping them out.  

3. Asian Longhorned Beetle  

The Asian longhorned beetle has a lot in common with our previous entry. Like the emerald ash borer, the Asian longhorned beetle was most likely introduced to the United States on untreated wood pallets from Asia. Both insects also share a taste for destroying trees from the inside out. Newly hatched Asian longhorned beetle larvae feed on the phloem — and eventually the sapwood — of a tree, creating large tunnels called pupal chambers as they mature. Infested trees die within 10 to 15 years.  

Far less picky than the emerald ash borer, the Asian longhorned beetle has been devastating hardwood trees in urban environments, including maple, birch and elm trees. This black and white beetle now threatens billions of dollars’ worth of recreation and forest resources. Although the Asian longhorned beetle is so far only in New York, Massachusetts and Ohio, all 50 states are at risk. 

4. Asian Citrus Psyllid 

You may not be familiar with the Asian citrus psyllid, but you’ve likely heard of their impact on Florida’s citrus industry. This mottled brown insect is a vector for Huanglongbing, also known as citrus greening, one of the most serious citrus diseases in the world. Infected plants produce green, misshapen and bitter-tasting fruit, which makes them unmarketable. An adult psyllid can transmit the disease to a citrus plant in as little as 15 minutes. Asian citrus psyllids have already devastated citrus industries in Asia and Africa, and they’re starting to do the same here in the United States, where they can be found in all citrus-producing states and territories.  

Since being discovered on Florida’s east coast in 1998, the Asian citrus psyllid has cost Florida millions of acres of citrus crops and billions of dollars in lost citrus production. The Sunshine State has gone from producing 80 percent of the nation’s non-tangerine citrus fruits to producing a little over half as a result of citrus greening. Chemical controls have kept the Asian citrus psyllid in check; however, this strategy is proving increasingly ineffective. Scientists and growers are searching for ways to mitigate losses due to citrus greening and continuing to research novel control methods for the Asian citrus psyllid.  

5. Brown Marmorated Stink Bug 

Since being discovered in Pennsylvania in 2001, the brown marmorated stink bug has spread throughout the United States and established a strong presence on both coasts. This rapid spread is thanks in part to this stink bug’s penchant for hitching rides on vehicles and cargo containers. There have been numerous sightings of the brown marmorated stink bug in Florida, and evidence suggests that it may have established itself near a peach orchard in Lake County. The brown marmorated stink bug is the perfect example of how an unsuspecting insect can cause widespread damage.  

Brown marmorated stink bugs present a threat on multiple fronts. Not only is this invasive species a nuisance to homeowners, but it’s also a major threat to farmers. Being a polyphagous pest, the brown marmorated stink bug can feed on numerous sources of food, including fruits, vegetables, nuts and row crops. Further complicating matters is the fact that the brown marmorated stink bug has disrupted integrated pest management (IPM) techniques, forcing growers to rely heavily on insecticides. Scientists are currently experimenting with pheromones and lights to attract and trap this invasive species.  


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