ORNAMENTALSAND
TURF
ORNAMENTALS
The information and recommendations in this newsletter are applicable to North Carolina and may not apply in other areas.
Sawflies received their name because the adults resemble flies and
the females have saw-like ovipositors they use to saw open leaves
or needles to lay their eggs inside. Redheaded pine sawflies lay
about 120 eggs, usually in the needles of one twig of southern
yellow pines and other hard pines. The females insert the eggs in
a row. From the eggs hatch tiny caterpillars that are much like
moth and butterfly caterpillars (the sawfly caterpillars have more
legs, however). Redheaded pine sawfly caterpillars are often
abundant locally and almost always feed gregariously. Large pines
may be noticeably defoliated and small trees may die. When mature,
the caterpillars usually crawl to the soil where they pupate in
small (1/2 inch), brown cocoons. Within a few weeks, small,
fly-like adults emerge and mate. There are four or five
generations each year. Pine sawflies overwinter as prepupae in
cocoons. Some prepupae develop the following year, whereas others
may wait two or more years before developing. There is additional
information on the redheaded pine sawfly in Insect and Related
Pests of Shrubs (AG-189), a North Carolina Cooperative Extension
Service publication that should be available in the county
extension centers in North Carolina. Also in the extension centers
are copies of Ornamentals and Turf Insect Note No. 7 that
provides suggestions for caterpillar control.
Greenstriped mapleworms are one of the more common caterpillar
pests of maples, although they usually are not a widespread pest.
Occasionally greenstriped mapleworms become locally abundant.
When fully grown, the caterpillars crawl to the soil and dig in to
pupate. A few weeks later, the pupae molt into beautiful pink and
yellow moths called rosy maple moths. These moths then lay masses
of bright yellow eggs from which hatches a second generation of
greenstriped mapleworms. Every few decades, these caterpillars
become abundant enough to cause significant damage to maples. I
have not seen this happen yet, but older literature refers to
episodes in which the first generation strips maples bare and then
just as a new flush of growth emerges, the second generation
emerges to defoliate the trees again. This type of defoliation can
seriously weaken maples to the point that borers may infest the
trees and finish them off. Sevin or some other contact insecticide
should provide adequate control of greenstriped mapleworms.
Bacillus thuringiensis should provide adequate control is it is
applied when the caterpillars are small in size.
Walnut caterpillars, immature stages of one of the handmaid moths,
are beautiful cinnamon brown moths with two inch wingspans. Walnut
caterpillars are widespread pests, and the caterpillars are found
on a wide variety of deciduous trees but mostly on walnuts, pecans,
and hickories. The moths emerge in the spring and summer and lay
their eggs in June and July. The larvae feed gregariously until
mature. Then they have the strange habit of crawling down onto the
trunk in a dense, fuzzy group to molt. Full grown larvae drop to
the ground and crawl around looking for a place to pupate. They
overwinter in the pupal stage. Trees completely defoliated two
years in a row by these pests may be stunted severely or killed.
Azalea caterpillars are the immature stages of one of the handmaid
moths. Young azalea caterpillars are small green caterpillars that
grow into purple and yellow-striped caterpillars. In the last
instar, they molt into large black and yellow-striped worms with
red heads and prolegs. They are sometimes called Labor Day
worms, because they are often discovered around Labor Day. Azalea
caterpillars are gregarious in the larval stage, which makes their
control relatively easy. However, because the caterpillars feed in
groups, they often completely defoliate a portion of a plant before
they are detected. There is only one generation of these insects
per year. The adult moths emerge in early summer and deposit their
eggs in masses of 80 to 100 on a leaf. As the caterpillars mature,
they do more damage. Most of the damage occurs in August and
September. Sevin, Orthene, Mavrik, and pyrethrin-based
insecticides should give adequate control of the caterpillars.
Additional information on azalea caterpillars is in Insect and
Related Pests of Shrubs (AG-189), a North Carolina Cooperative
Extension Service publication that should be available in the
county extension centers. Also in the extension centers are copies
of Ornamentals and Turf Insect Note No. 7 that provides
suggestions for caterpillar control.
In the past week, there has been a dramatic increase in the
abundance of armyworms and cutworms in turfgrass. These insect
pests seem to be responding well to the recently occurring wet
weather in many areas. They represent a serious threat to
turfgrass because their populations often develop unnoticed until
the caterpillars become fairly large in size. Then they appear to
suddenly attack the grass and virtually consume it at the ground
level. In some cases, the caterpillars are moving from higher cut
turf areas. It is important to monitor caterpillar populations in
quality turf areas. This can be accomplished relatively quickly
using a soap flush technique. Two tablespoons of liquid
dishwashing detergent added to two gallons of water in a sprinkling
can should be applied over a square yard area. As the water soaks
in, observe the turf for the presence of caterpillars emerging from
the thatch. Watch the area carefully for 3 to 5 minutes. This
technique works well for early detection.
Web page last updated on August 12, 1996 by Stephen J. Toth, Jr..
