Environmental Engineering Reference
In-Depth Information
Fig. 11.10. Leaf- and shoot-feeding larva of sod web-worm.
tion of the turf and other parts of the landscape. For example, the
population of grubs can be estimated from the number of adults feeding
on host plants or from the presence of beak holes in the sod produced by
birds searching for larvae. Another example is presence of moths flying
in front of shrubs shortly after sunset, a good indication of approaching
infestation with sod web-worms.
Pests are never evenly distributed throughout the turf; rather, they
occur in isolated spots or pockets. Frequently, certain areas, such as
moister low spots, elevated dry spots or windbreak areas are more
vulnerable to certain insects than others. As a result, these areas should
be inspected first and more thoroughly. Turf thinning, dead or dying
patches, chewed or frayed grass blades, and distinctive webbing or faecal
pellets are potential evidence of insect pests. Still, the best indication of an
insect infestation is physical presence of the insect.
Numerous sampling techniques are utilized to look for insects infest-
ing turf. For example, a floating technique is used to sample arthropods,
especially chinch-bugs,
Blissus
spp. One end of a plastic cylinder or large
can (15-20 cm in diameter), open at both ends, is forced into the turf
surface and filled with water. Because water continuously escapes, water
must be added for 5-10 min, which is usually sufficient for chinch-bugs
to float to the surface, be recognized and be counted (Fig. 11.11). Another
sampling technique involves use of 20-40 ml of laundry detergent mixed
with 5-10 l of water. Minutes after application of this solution to turf,
caterpillar-type larvae emerge to the surface, where they can be identified
and counted. The most destructive method, soil sampling, is sometimes
necessary for confirming the presence of soil-inhabiting insects such as
