Glossary new


The third and often largest part of an insect’s body, located closest to the tail end of the insect.  It is made up of several similar-looking segments and often bears a pair of jointed, terminal appendages called the cerci.


Final life stage of an insect, when it is fully formed and capable of reproducing.

Alternate host

A plant other than the main host that is required for a pathogen or pest to complete its lifecycle.  For example, the white pine blister rust pathogen needs to infect a plant in the genus Ribes before it can make a pine tree sick.



Pair of long, thin body parts on the heads of insects that are used to feel and smell.


A large group of animals with hard shells on the outsides of their bodies, legs with joints, and no bones inside their bodies. Insects, spiders, centipedes, and crabs belong to this group.


Type of deciduous tree with compound leaves arranged opposite one another along each branch. This tree, whose wood is used to make baseball bats, is threatened by a bug known as the Green Menace!

Asian Longhorned Beetle

This invasive bug can measure over 1 inch (2.5 centimeters) in length, and has six legs, a black body with white spots, long and banded antennae, and sometimes has blue feet!


The outside cover of the trunks, branches, and roots of woody plants.


An insect with a pair of hard front wings that cover a pair of thin wings.

Beneficial Insect

An organism that is helpful to plants by eating pests that would otherwise cause damage. Ladybugs are an example because the eat aphids which damage leaves.


A reduction in pest numbers caused by natural enemies.  Usually, humans play an active role in biocontrol by introducing predators, parasitoids, or pathogens to attack the pest needing to be controlled.


A tree known for its papery thin and smooth bark that is threatened by Asian Longhorned Beetle (ALB).


A disease that destroys parts or all of a plant.


Any of a number of insects that chew, dig, and burrow into plants.


The collection of young insects in a colony, made up of eggs and larvae


Thin layer of cells between the bark and wood of a tree that gives rise to both. Burrowing insects like Emerald Ash Borer (EAB) can damage this tissue which weakens and eventually kills the tree.


A defined area (often sunken or discolored) that is diseased or has been killed by a pathogen, especially on a woody stem. Cankers caused by Sudden Oak Death ooze a sticky red liquid, and those caused by white pine blister rust have a border of white or orange “blisters,” which contain spores of the pathogen.

Cerceris wasp

A native ground-nesting wasp that preys on EAB. This bug is starting to be used as a tool for biosurveillance, or using another species to survey for a pest species. Finding a nest is a pretty good indicator that EAB is nearby!


Small appendage, occurring in pairs, at the end of the abdomen of some insects and other arthropods

Chestnut blight

A disease that almost completely wiped out a tree that made up 25% of the forest canopy on the east coast 100 years ago


A collection of several individual organisms, normally of the same species, that live very close together.


A mixture of decaying plant material, such as dead leaves, mulch, manure, or vegetable matter.  Coconut rhino beetle adult females often lay their eggs in compost heaps.

Compound leaf

A distinguishing feature of ash trees, these are made of 5-11 leaflets are found opposite one another along a branch


A symptom of plant disease that appears on tree twigs and branches

Dutch elm disease

A disease that has affected common vase-shaped street trees in almost all 50 states in the U.S. since its introduction in the 1930s


The first life stage of an insect which begins as one cell and matures into a larvae


A vase-shaped tree often used to line sidewalks and provide shade that is threatened by ALB

Emerald ash borer

Also known as “the green menace,” this invasive bug was first found in the Michigan in 2002 and has already spread to 14 states and several parts of Canada and killed millions of trees!


This term is used to describe a species that is in danger of dying out.


The scientific study of insects

Epicormic sprouts

Type of growth that occur on tree trunks or large branches that have been damaged by EAB and Laurel Wilt

Exit hole

Wound or opening in the bark where a wood-boring insect has chewed its way out of a host tree. These often have a very specific shape that can help tell who was there!

Exotic Species

An organism that has been introduced from a foreign place


A material burned in woodstoves or campsites for heat. Don’t transport this because it can carry sneaky stowaways and help spread pests like ALB, EAB and the redbay ambrosia beetle to new areas!

Foliar host

Any one of a wide number of common ornamental and forest plants that can carry diseases like Phytophthora ramorum but only exhibit minor symptoms like leaf spot. Although they rarely die as a result, these plants can play a major role in transmission through dispersal of spores from infected leaves!


Sawdust like material that wood boring insects like ALB, EAB and the redbay ambrosia beetle push out of the tree as they burrow. This can be a clue that the tree is under attack or already infested!


The latin name for the genus of trees to which Ash belongs


The leaves or leaf-like parts of palm trees or ferns.  Often they have many divisions, which may look like many small leaves.  Palm fronds attach to the trunk, and it is at this attachment point that the coconut rhinoceros beetle often burrows into the tree to feed on sap.


One of a large group of living things that are similar to plants but cannot make their own food using sunlight in the way plants do. They help decompose dead plants and animals and include mushrooms, yeasts, and molds.


An abnormal swelling or growth on a plant, caused by an insect, injury, bacterium, or the like.


Tunnels that adults or larvae of wood boring insects like EAB and PSHB create when burrowing in the tree’s wood. These can either be found just under the bark of infested trees or throughout the entire branch or trunk, depending on what the pest’s lifecycle is like.


A group of different but closely related plants or animals. This unit contains more organisms than a species but fewer than a family


To cut away or kill the living tissue in a ring around a plant’s branch or stem, often causing it to die.


The young form of an insect, especially a beetle, that looks like a soft, thick worm with six small legs.



The first or leading part of an animal body. In invertebrates (like insects), the head contains eyes, mouth parts, and other organs

Hemlock woolly adelgid

A non-native insect that threatens to kill 80% of the an evergreen green native to the Appalachians


Host tree for ALB that is named for its smooth, brown nuts and has large compound leaves and beautiful flowerclusters.

Host species

A term for any plant that is vulnerable to or can harbor a plant pest or disease


The process of inserting a small amount of fungus or disease to start a new colony


A small animal with a hard covering over its body, which usually consists of three parts. Most of these animals also have three pairs of legs and one or two pairs of wings. Examples include bees, ants, butterflies, beetles, and flies.