Environmental Engineering Reference
In-Depth Information
Egg
Simple metamorphosis
Nymphal stages
Adult
Egg
Larva
Pupa
Complex metamorphosis
Adult
Fig. 11.9. In simple metamorphosis, the eggs hatch into nymphs that resemble
adults. In complex metamorphosis, eggs hatch into larvae, which then become
pupae, which in turn metamorphose into the adult form.
smaller and not fully developed. Most insect pests of turf undergo full
metamorphosis, and the larvae rather than the adults cause the damage.
In those that undergo simple metamorphosis, the nymphs usually feed as
they grow.
Some insects feed by chewing and others by sucking. Chewing in-
sects ingest plant tissues or organic residues directly. Sucking insects use
piercing mouthparts to poke through the surfaces of leaves, stems or
roots and suck the plant fluids.
Insects presenting a direct threat to the turf-grass community are
root-feeding insects such as grubs, billbugs and mole-crickets as well as
shoot-feeding insects like web-worms, army-worms and chinch-bugs
(Fig. 11.10). Burrowing insects such as ants and cicadas are considered
a nuisance but do not cause direct damage.
Unlike weeds or diseases, insects are not very effectively controlled
by preventive measures or cultural practices. In fact many insects are
more likely to attack well-maintained turf because healthy plants with
lots of fresh growth provide a plentiful source of food. To manage insect
pests effectively, turf managers must have a working knowledge of their
life cycles and habits in their feeding areas.
Insect detection
Before any control is attempted, the presence of insects must be detected.
Accurate diagnosis of insect infestation requires periodic visual observa-
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