which occur in lawns are beneficial insects. They provide a form
of natural control of pest insects or assist in the breakdown of
organic matter so nutrients can be returned to the soil.
are relatively mobile insects that search out prey. Some predatory
insects (like the assassin bug) have sucking mouthparts which penetrate
the soft body of the victim and suck out the internal fluids, leaving
only the outer shell behind. Other predatory insects (like ladybird
beetles and ground beetles) have chewing mouthparts and feed on
the entire body of the victim. Predators will feed on several victims
during their lifetimes. Some of the more familiar predators which
occur naturally in New England lawns include:
These may be the most common predators on lawns in New England.
The most common species are slightly smaller than Japanese beetles
and are generally a shiny bronze or tan or green color. Both adults
and larvae feed on soft-bodied insects and various caterpillars.
Ground beetles usually are very quick moving and can "seek and destroy"
Rove beetles may not be familiar to many people, but they do
occur commonly in turfgrass areas. They are somewhat more elongated
than other beetles, and the hindwings are not fully expanded. They
feed on a variety of soft-bodied insects.
Spiders are surprisingly common and active in turf areas and
are very efficient predators. While they are not insects, many species
of spiders are definitely beneficial in the garden or lawn, feeding
on a wide range of immature insects and mites.
species of ants are carnivorous, and seek out insects and other
soft bodied organisms with which to provision the nest. In addition,
ant activity often can help in the general breakdown of organic
matter and the formation of soil. However, if ant activity becomes
excessive, the ants may become a nuisance or the soil may dry out
and turf damage will result.
group of beneficial insects is the parasites. These are small insects
(generally smaller than the host) which develop inside or on the
body of a single individual. The adult female finds a suitable host
and lays her eggs on the outside of the body or inserts the eggs
through the skin into the internal tissue of the host. The immature
parasites feed on the organs and fluids inside the victim and gradually
weaken and kill the host.
There are many
parasitic wasps which occur naturally in New England and are active
in lawn settings. Wasps such as Scoliid (family: Scoliidae)
and Tiphiid (family: Tiphiidae) wasps are adapted
to lay eggs in softbodied insects and do not bite or sting people.
Scoliid wasps are about 16 mm (5/8 inch) long and blue-black, with
blackish-purple wings. They have a yellow stripe on each side of
the abdomen. Their bodies are fairly hairy and the back part of
the abdomen is covered with reddish hairs. Tiphiid wasps are black
and somewhat hairy with short, spiny legs. Both wasps are generally
seen flying over the lawn during the day, leaving in early evening.
Scoliids and Tiphiids are beneficial wasps in that they parasitize
grub populations. They are not aggressive and generally do not attack
humans. Adults are often seen on golden rod flowers in the late
insects are very sensitive to insecticides, so whenever a general
insecticide is applied to control a pest species (such as Japanese
beetle grubs or chinch bugs), the
material will usually have a detrimental effect on the beneficial
organisms, often for at least a few weeks. Consider using alternate
methods of pest management, biological control agents (if available
and suitable) or providing optimum cultural conditions so that the
lawn can tolerate higher levels of pest activity without visible
loss of vigor. If an insecticide application is deemed necessary,
make spot treatments rather than broad scale applications if at
the statement, "The only good bug is a dead bug," could not be further
from the truth. Be sure you have an accurate identification of the
insects in question and only attempt to control those which really
warrant attention. There are in fact many "good bugs" out there!
Let them help!
from the University of Massachusetts Extension, 1999