WWW.CLEMSON.EDU/PSAMEDIA
  
EDITOR'S NOTE: FREE digital photos available from 
gsngltn@clemson.edu
  
DATE:   5/31/01     
WRITER: Dr. Clyde Gorsuch, Clemson Extension entomologist;
        (864) 656-5043
EDITOR: Giles Singleton, (864) 656-3876; gsngltn@clemson.edu
  
Crawler Control:
Dealing with two landscape pests
  
     Clemson -- What carries its house with it and can kill Leyland
cypress, juniper, and other evergreen ornamentals? Bagworms.
     The caterpillar stage of this insect feeds on a wide range 
of ornamental shrubs and trees. Immediately after hatching, the 
tiny caterpillars spin a silk bag around them and then tie bits of 
the host plant into the silk. This provides protection from the 
weather and natural enemies.
     Especially when the caterpillars are small, they are so well
camouflaged that most people never realize they have a serious 
problem. As a caterpillar grows, it continues to enlarge the bag, 
which is about one-and-a-half inches long when the caterpillar 
matures.
     When the caterpillar is ready to change into an adult moth, 
it ties the bag to a twig or other surface with silk. At this time 
the caterpillar may migrate to the side of the house, other shrubs 
or to a fence post. However, you can always tell what the real host
plant was by looking at the plant material in the bag. 
     The males turn into a dark gray moth that leaves the bag and 
flies around in search of a female. The females develop into a legless,
wingless adult that is nothing more than an egg-laying machine. 
After mating, the female produces as many as 1,000 eggs and then 
dies.
     The eggs spend the winter inside the bag and begin to hatch 
in May. There is a single generation a year.
      Control can take several directions. For a light infestation, 
a person can cut off all of the bags during the fall and winter months.
If the bags are put in a container and placed in the trash, the
caterpillars will not survive.
       In May and early June, when the caterpillars are still fairly
small, one of the Bacillus thuringiensis materials, such as Dipel, 
can be used very effectively. Once the bags reach an inch long a
regular insecticide, such as acephate (Orthene) or carbaryl (Sevin),
should be used.
     To see a photo of a bagworm, go to:
http://entweb.clemson.edu/cuentres/cesheets/ornament/ce68.htm
     Scale insects are another major problem on many types of
ornamental trees and shrubs, as well as on fruit trees.
     Adult scales do not have legs and are attached to the host 
plant. They suck sap from the host plant and may produce a syrup-
like substance called honeydew. Black sooty mold may grow on the
honeydew. 
     There are two types of scales. Armored scales produce a 
separate cover that protects them from the environment. Others, 
called soft scales, simply have a thick outer "skin" that protects
them. 
     Scale insects will lay eggs under their bodies. When the eggs
hatch, a tiny insect about the size of the period of a sentence 
crawls around on the plant, looking for a place to settle and begin
feeding.
     The "crawlers" are usually a yellowish to pinkish color.
     This is the stage that is easiest to control. To detect the
crawlers, clean off any scales on an infested branch. Make a band 
about one inch wide.
     Wrap a length of black plastic electrician's tape around the
cleaned area and coat the tape with petroleum jelly. Check the
petroleum jelly at least every other day for the presence of 
crawlers. A magnifying glass may make it easier to see them.
     Once you find the crawlers, the shrub should be treated with 
an insecticide, such as acephate (Orthene). Other treatments include
insecticidal soaps and summer oils. Complete coverage is essential 
for good control. 
                           ******************
     If you have gardening questions, write to PSA Media Relations,
A-101 Poole Agricultural Center, Clemson University, Clemson, S.C.
29634-0129 or search our website at: www.clemson.edu/psamedia.
                            END