Target Pests

You can become a more effective First Detector by familiarizing yourself with invasive pests and pathogens known to exist in the U.S. If you think you have encountered one of the species or disease complexes listed below, report its presence here.

 

 

Vocabulary

Host: the affected plant on which a pest or pathogen completes its life cycle
Pathway: how a pest or pathogen moves or expands its range; this may be natural or human-driven

 

Pests in Your State

Learn which pests could be found in your state thanks to USDA-APHIS's Hungry Pest Tracker!


 

Emerging Threats

Some plant pests and pathogens not known to be present in the U.S. could threaten our plant resources if introduced.

Learn More

 

Asian Longhorned Beetle

The Asian longhorned beetle (Anoplophora glabripennis or ALB) is an invasive wood-boring insect. The adult beetle has a distinctive appearance and grows to 1.5 inches in length. The body is shiny jet black with irregular white spots. Antennae are typically longer than the body—up to 2 ½ times the body length—and banded black and white. The beetles have six legs, sometimes with bright blue on the legs and feet.

ALB cause the most damage during the larval phase of their life cycle, which is spent entirely within the wood of trees. The larvae are light cream-colored and do not have legs or a distinct head.

Emerald Ash Borer

The emerald ash borer (Agrilus planipennis or EAB) is an invasive wood-boring beetle. Despite their flashy color, these beetles are difficult to spot in the wild! Adult EAB are bright, metallic green, about 1/2″ long and 1/8″ wide with a flattened back. An adult EAB fits on the head of a penny.

EAB only harm ash trees during their larval stage. As they tunnel beneath trees' bark, they disrupt the plants' food and water transport, eventually killing the trees. The larvae are creamy-white and wormlike with flattened segments shaped like nested bells.

European Gypsy Moth

The European gypsy moth (Lymantria dispar dispar or EGM) is a relatively large moth and easy to identify from native moths. The sexes are distinct in both appearance and behavior. Male moths are brownish and can be seen flying during the day. Male EGM have a wingspan of about 1 ½". Female EGM do not fly and are a bit larger and creamy white in color. Both sexes have a characteristic mark on the forewings that consists of a blackish arc and an accompanying dot near the apex of this arc. This arc-dot combination is diagnostic of Lymantria and easily separates them from native moths. Females lay eggs on tree trunks, outdoor furniture, and other outdoor items then cover them with buff to cream-colored hairs. Egg masses will be visible through winter.

Newly hatched larvae are black with long hairs. Older larvae are distinguishable from all native caterpillars by the presence of five pairs of blue raised “bumps” or spots followed by six pairs of raised brick-red spots along their backs. They are very hairy.

Giant African Snail

Giant African snail (GAS) refers to several snail species from East Africa. One species, Lissachatina fulica, can grow almost eight inches long. This species has a long, conical shell which usually consists of 7–9 whorls. The largest whorl can measure five inches in diameter which is about the size of an average adult’s fist. Shell color can vary depending on the snail’s diet but usually consists of brown and tan stripes with variations of light brown and cream. Often the tip of the shell is lighter or white.

GAS are very prolific and just two snails can produce an infestation in a relatively short time. Each snail contains both male and female reproductive organs and can produce up to 1200 eggs/year.

Adult snails are typically nocturnal—feeding at night and seeking shelter during the day time. They become more active during damp or humid weather. Juvenile snails may feed during the day. In heavy infestations, snails will be visible in the open, any time of day and are considered a nuisance.

Immature snails are smaller and may resemble some native snails. It is best to contact an expert if you suspect a large snail could be a giant African snail.

Hemlock Woolly Adelgid

The hemlock woolly adelgid (Adelges tsugae or HWA) is a very small, aphid-like insect that feeds at the base of hemlock needles. Adults are red to purple-black and about 1mm long; nymphs are about the size of the period at the end of this sentence. HWA is most visible towards the end of adulthood, when they cover themselves in a white, cottony wax where they lay up to 300 eggs. Eggs hatch into nymphs which crawl or are moved by wind, birds and other animals to another hemlock needle, where they feed on the starches the needle needs to live. The adelgid stays in that spot for the rest of its life. Although many eggs are produced, mortality of the nymphs can be as high as 90% since their dispersal method is mainly dependent on chance. HWA has two generations a year so populations can build rapidly.

Huanglongbing

Huanglongbing (HLB), also called citrus greening, is one of the most threatening diseases to citrus plants in the U.S. and worldwide. The HLB bacterium is spread by the tiny, invasive Asian citrus psyllid and may infect a wide range of citrus and closely related species. The disease is fatal, and presently there is no known cure.

Laurel Wilt

Laurel wilt is a deadly disease of redbay and other native plants in the laurel family. The disease is caused by the fungus, Raffaelea lauricola, which is introduced into host trees by a non-native insect, the redbay ambrosia beetle, Xyleborus glabratus. The fungus quickly plugs the water-conducting cells of an affected tree and causes it to wilt.

This insect vector attacks healthy trees. These beetles can be difficult to identify so a specialist should be consulted for positive identification.

Oak Wilt

Oak wilt is caused by the fungus, Bretziella fagacearum (formerly Ceratocystis fagacearum). It was first identified in 1944 and its origin is still uncertain. The fungus grows in the vascular tissue of the tree—this cuts off the supply of water and causes the tree to wilt and die. As the fungus grows it spreads below ground through natural root grafts to infect healthy oak trees. Once the fungus has killed a tree it may produce a mat of fungal spores under the bark. When pressure builds in this spore mat it causes the bark to split. Several species of sap beetles are attracted to the strong fruity odor produced by the spore mats. The beetles feed on and tunnel through the mats they get covered with spores. Disease spreads when beetles covered in oak wilt spores transfer these spores to new host trees. The spore mats are especially common in infected red oaks.

Spotted Lanternfly

Spotted lanternfly (SLF), an invasive insect native to China, India, and Vietnam, threatens U.S. agricultural, logging, and tourism industries. First detected in Berks County, PA in 2014, the pest demonstrated its detrimental impact upon plant growth and fruit production as its populations exponentially increased and spread in 2017.

Red hindwings, striped with white and tipped in black, faintly saturate the semitranslucent, spotted, gray forewings of this 1" long adult leafhopper. Young nymphs are black with white spots becoming more red as they mature.

Sudden Oak Death

Phytophthora ramorum is a water mold pathogen that causes two types of disease. On trunk hosts, it causes the disease known as sudden oak death, a forest disease that has resulted in widespread dieback of several tree species in California and Oregon. On understory plants P. ramorum is a foliar and twig disease which infects but does not kill a wide variety of ornamental plants; on foliar hosts, P. ramorum is referred to as ramorum blight or ramorum dieback.

Thousand Cankers

Thousand cankers disease (TCD) results from the combined activity of two organisms; a newly described fungus, Geosmithia morbida, and the walnut twig beetle (WTB), Pityophthorus juglandis. Trees are eventually killed by overwhelming attacks of the walnut twig beetle and subsequent cankers that girdle branches.

WTB are tiny yellowish-brown bark beetles, about the size of a small flea or a broken piece of lead from a mechanical pencil. See image gallery below.