Remember how much fun it was to chase
fireflies when you were young? Once you caught a firefly, you would hold it in
your hand to watch the flickering light for a few moments and then release it
unharmed to fly away.
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| Fireflies at night, taken with a cell phone. |
Interestingly, fireflies do more than generate
entertaining childhood memories; they also help control some pests in the
garden. On summer nights, glow worms (luminescent firefly larvae) often emerge
from their underground homes to forage for food. A typical menu includes slugs,
snails and caterpillars including cutworms. The larvae feed much like a spider
by injecting a paralyzing toxin into their prey; then, injecting digestive
juices to dissolve the prey and allow it to be more easily consumed. The adults
probably feed on plant nectar to sustain their energy requirements.
There are several theories about why
fireflies glow. One is that the flashing light is a homing beacon for the
opposite sex. The male flies around flashing the signal to attract a female’s
attention. A female on the ground or on low-growing foliage will signal back
when a male visits her vicinity. To avoid confusion, each firefly species has
its own specific signal to attract a mate.
Another theory is that firefly larvae
use their luminescence to warn a potential predator that they taste bad. Larvae
contain defensive chemicals in their bodies. When disturbed, larvae also
increase their glow’s intensity and frequency.
Typical nighttime habitats for adults
and larvae take place in rotting wood or other forest litter, or on the edges
of water sources such as streams, ponds, marshes and ditches. The highest
species diversity is in tropical Asia and Central and South America.
Incidentally, some Asian species have tracheal gills that enable them to live
under water where they feed on aquatic snails.
To attract fireflies to your property,
reduce or eliminate lawn chemicals. Add low, over-hanging trees, tall grass and
similar vegetation to give adult fireflies a cool place to rest during the day.
Reduce extra lighting on your property because this light interferes with
fireflies’ luminous signals, making it harder for them to locate mates in the
area. Fireflies also determine the time of night they’ll flash by the intensity
of ambient light. This is why you don’t see many fireflies flashing on clear
nights with a full moon.
