Legends of greatness and evil abound in the west. When it comes to the 6-legged westerners
there is no more storied creature than the grasshopper. The stories of their swarms are epic and
biblical – skies dark as night and crops devastated in moments. The Hopi tell their children that the
grasshopper will bite off the noses of those who disobey elders or violate
taboos. Other tribes claim that the
grasshopper predicts bad weather or brings evil with it. Even Aesop featured the grasshopper in his
fable of the Grasshopper and the Ant
– using the grasshopper as counterpoint to the industrious and hardworking
ant. Needless to say, the grasshopper
doesn’t survive the harsh winter because of his summertime idleness and folly.
Grasshoppers present an obstacle for those of us who were
taught to look for the best in every situation.
I’ve always felt that there isn’t much good that can be said about
grasshoppers, but I’ve become curious about where they fit in the scheme of
things and whether I need to change my attitude.
It turns out there are more than 400 known species of
grasshoppers in 17 states of the western U.S.
Only 2 dozen of these species are considered a pest. Several species are considered as beneficial
insects because they consume undesirable plants. The other grasshoppers are
somewhat benign.
Even the ‘bad guys’ have some good points:
- As an herbivore, grasshoppers link plants to the rest of the ecosystem and his helps biodiversity.
- Their droppings (frass) contribute nutrients by turning the plant material into fertilizer.
- They are a food source for birds, spiders, lizards, and rodents.
However, as with all things in the garden, I’m looking for
balance. I think that there is enough
vegetation to go around. But I want
those bad guys to exist outside my gardening perimeter. I realize now that before I try to manage the
grasshoppers in my patch, I need to identify what species I’ve got and determine
whether they are actually harmful to my cultivated plants. One excellent clearinghouse of identification
guides is provided by the USDA and can be found at this link: http://www.sidney.ars.usda.gov/grasshopper/ID_Tools/index.htm.
A little about their
life cycles
Understanding the life cycle of a grasshopper can help you identify
the species you have and to determine when treatments will be most effective. Taking this step can save time and
money. Typically, grasshoppers emerge in
late spring and remain active through autumn.
Treatment at any time will help, but to gain optimal control it is
important to watch for them in their earliest, above soil stages.
All grasshoppers begin life as an egg. The eggs are laid in soil, in tight clustered
pods and are usually well hidden in specific habitats. The eggs begin to incubate immediately. Depending upon the species, the embryos begin
to develop and then based on environmental cues (temperature is a major cue)
enter a state of diapause and cease growing until favorable incubation
temperatures are reached. Both the
diapause and incubation inducing temperatures differ from species to species.
Generally temperatures between 50 oF and 55oF
trigger development to restart. Once
optimal temperatures are reached grasshoppers continue to incubate in soil and will
hatch as nymphs. All grasshoppers develop
through a process of gradual (simple) metamorphosis, there is no larval
stage. The hatched nymph looks like the
adult except it is smaller, has no wings, fewer antennae segments, and only
rudimentary genitalia. Depending upon
their species, as grasshoppers grow and develop they molt (shed) their outer
skin 4 to 6 times during their nymphal (immature) life.
Control options
One way to keep grasshoppers away from the plants you don’t
want them to consume is to provide some beneficial habitat in a place where you
are happy for them to be. An island of
dense, native grasses and flowers is a great way to help keep them away from
your more precious plants.
When grasshopper populations exceed your tolerance, there
are two natural and effective organic methods for controlling them.
- Nosema locustae - naturally occurring fungus that weakens and kills when eaten.
- Beauveria bassiana - derived from naturally occuring fungi in the soil cause muscadine disease when consumed.
Nosema locustae is
available under two labels: Semaspore
and NOLO Bait. These products are
effectively the same. The Nosema locustae is embedded on flakes of
bran that act as bait to the grasshopper.
Once consumed, the grasshopper develops a disease, is weakened, consumes
less, and eventually dies. In 2 – 4 weeks,
50% of the population will be dead. It
is most effective when grasshoppers are ½” – ¾” in size. Nosema locustae is only fatal to grasshoppers
and their close relatives such as crickets and mantids.
Beauveria bassiana
is available as a liquid under two product names: Mycotrol O and Botanigard ES. It is available as a wettable powder as
Botanigard 22WP. This product causes
white muscardine disease in a wide variety of pest insects including thrips,
aphids, whitefly, psyllids, and fire ants.
When either of these products are applied, pay close
attention to grassy areas of untilled ground, to southern slopes or any other
location known as a grasshopper hatching bed.
While grasshoppers may be considered a scourge, they have
some interesting and quirky behaviors.
I’d like to leave you with a few of these so you might see why they are
quite fascinating:
- Females lay eggs in holes that they dig with their abdomen.
- Some grasshoppers spit a bitter, brown liquid as a defensive behavior - they may spit at you when you handle them.
- Before molting, grasshoppers do not eat.
- During molting, they swallow air to build pressure to break the cuticle of the old 'skin'.
- Each grasshopper species has an individual song produced by rubbing or flicking the lower back legs on their forewings.
- Some species have elaborate courtship routines performed by the males. Some include posing using wings and legs while others wave brilliantly colored wings to woo their mate.
In spite of their bad reputation, I can’t help but feel
respect and some admiration for an insect that has achieved fame in so many
cultures and breeds such fear and loathing in the hearts of gardeners and
farmers everywhere. But when it comes
down to the battle for my plants – I am happy that there are control methods
that won’t harm the good guys in my garden.
