Question
I have a crepe myrtle tree.  It is infested with insects that seem to be attached to the branches and trunk of the tree.  I've also noticed sap on the sidewalk near the tree.  The insects are about the size of lady bugs. They have a segmented body and are striped black and red.  What are they and what do i use to control them.  This is the first time I've seen this ins the 10 years I've been in the house.

Answer
The insect causing the sap is a scale. These insects suck the plant juices from the twigs and secrete a sticky substance called honeydew which is high in sugar content and usually a black sooty mold will be growing on the honeydew. The black and red one sounds like a lady bug which is a predator of the scale. These beetles feed on the scale insects.
To control the scales I would use a systemic insecticide either a spray for the foliage or a soil applied one.

Foliar sprays: Leaf treatments are best applied after the crawlers hatch from the eggs and begin to settle on new foliage. Beginning in late April and again in mid-August, examine the leaves on the infested plants every 1 or 2 weeks for newly settled nymphs. They will appear small, white and starlike as they begin secreting their wax coating. You may need to spray the leaves several times in 7- to 10-day intervals or as directed on the product抯 label. This spray schedule will protect the new foli-age through the period of egg hatch, particularly if it is the type of insecticide that offers little or no residual (long-lasting) activity, such as insecticidal soap or horticultural oil. For a longer period of control, use a contact systemic foliar spray such as products containing acephate (example: Orthene?Tree, Turf and Orna-mental Spray). This type of pesticide kills insects on contact, but it is absorbed into the leaf tissue, providing a longer period of control.

If you choose a soil-applied systemic insecticide, such as one containing imidacloprid (for example, Merit? Bayer Advanced?Tree & Shrub Insect Con-trol), apply it before egg hatch to allow the active ingredient to be moved from the soil through the roots and into the leaf tissue. The scales that are attached to the branches or twigs may be unaffected by this systemic soil treatment. Those killed by the insecticide may persist for a period of time before falling off. Carefully follow the directions on the product label.

Check with your loacl nursery/garden type store for a systemic for scales on trees.