The external signs of ambrosia beetles are small piles of white boring dust, or "frass" on the surface of the target plant.  The frass can also look like toothpicks emerging from the entry holes on the trunk of the target tree. Often times you will find what looks like sawdust at the base of a tree infested with ambrosia beetles. The term "ambrosia" refers to the fungus that the insect carries with it into the host plant. Growth of the fungus in the wood produces a black and gray stain surrounding the beetle tunnels.

Leaf curling and discoloration is actually not the main problem caused by aphids on most ornamental landscapes. In fact, the main problem is more of an aesthetic issue called Sooty Mold. Aphids excrete a sticky, shiny substance called "honeydew" all over the plants they feed upon. Later in the Summer, this honeydew is colonized by sooty mold fungi. The fungi feed on the honeydew and not the plant, so very little damage is actually done to the plant. The sooty mold turns much of the plant soot black. The honeydew from the aphids also tends to coat anything under the host plant. It is not uncommon to see your patio furniture, grill, or deck turn sooty black late in the summer if you have a crepe myrtle with aphid activity overhanging any of these things. 

 Bagworms:

Bagworms mainly feed on needled evergreens such as Leyland cypress, juniper, and arborvitaes. They are most active in the late summer. They can cause broad spread defoliation to host plants. 

Most all needled evergreens have older brown needles inside the green newer growth. Bagworms feed on the new, green needles, exposing the brown material inside the plant. They also cause a good amount of the newer green needles to turn brown. Most evergreens are very slow to repair the damage caused by bagworms. In many cases it takes multiple seasons for a plant damaged by bagworms to repair the damage caused. 

Lacebugs feed on a variety of Southeastern ornamentals, but are most often found on the undersides of azalea leaves. Lacebug damage appears on the upper leaf surface as white to yellow chlorotic spots. The lower leaf surfaces will be cluttered with black spots and the old cast skins of immature lacebugs.

Spraying the tops of the leaves with a contact insecticide does little to control lacebugs because they congregate on the undersides of the leaves and are often protected from contact with the control product. Care must be taken when spraying for lacebugs to treat the undersides of the leaves predominantly. 

Aside from the discoloration that occurs with a severe infestation, lacebug damage detracts from the host plant's ability to produce healthy blooms during its flowering season.

Leaf miners feed on fleshy soft leaf tissue. The damage looks like tunnels have been carved through the insides of the leaves. Another form of leaf miner damage looks like small holes with brown or discolored edges over the surface of the leaves.  Although the leaf miners do not generally move from leaf to leaf, a heavy population of these insects can cause widespread aesthetic damage to the host plant.

Control of leaf miners can be best achieved in the late summer before the young insects move inside the host plant's leaves. Systemic controls can also be used when they are actively feeding in the spring. 

Extensive defoliation can occur to oak trees between May and September due to oakworm infestations. Young larvae chew all the way through the leaves, and cause a skeletonized look on oak trees.

Oil applications and other forms of egg control greatly reduce the populations of oakworms from season to season. 

Laurels, privets, euonymus, and hollies are the main plants targeted by scale insects in the Southeast. They are often misidentified as some sort of white powdery fungus because of the way they coat the leaves, limbs and branches of their host plants. They suck nutrients from the leaves and stems of the host plant. The damage is seen as broad spread browning and curling of leaves.

Scale insects secrete a protective covering over their bodies. This covering protects the scale and makes control difficult. Scales insects are most easily controlled when insecticide applications are timed during their early development stages.

Scale insects reproduce very quickly, and severe infestations can kill host plants in a very short time period. 

Spider mites are most often found on junipers, rhododendrons and cotoneasters in the southeast. Spider mites cause yellowing of leaf and browning of needle material by sucking out the chlorophyll. They are so small they can barely be seen with the unaided eye.

Tent caterpillars are commonly seen in the early spring and throughout the summer on many different varieties of trees. 

They construct  webs or "tents"  in the crotch of small limbs on their host plant. This tent serves as a refuge for the larvae during the night and during rainy weather.

These insects are voracious eaters. They, like the Oakworm, eat completely through the soft, fleshy leaf parts leaving the leaves with a skeletonized look. 

Gardenias and privets are the most heavily affected by whiteflies in the Southeast. Whiteflies, like aphids and spider mites, are also sucking insects. They excrete a sticky, shiny substance called "honeydew" all over the plants they feed upon. Later in the Summer, this honeydew is colonized by sooty mold fungi. The fungi feed on the honeydew and not the plant, so very little damage is actually done to the plant. The sooty mold turns much of the plant soot black. 

Whiteflies often occur in tremendous numbers. When a heavily infested plant is disturbed, the air is filled instantly with a white cloud of these insects.