A Sure Sign of Summer: Lightning Bugs

Weekly Newspaper Article for The News-Democrat, Carrollton, KY

Lightning Bug (R Bessin 2000, University of Kentucky)

Lightning bugs.  What adult doesn't have memories of chasing and catching these fascinating little insects?

When my brothers and I were little, we spent many hours chasing bug and bug, and placing them in a jar with holes punched in the lid.  Then, we would sit in a dark room and watch these glowing wonders.

Lightning bugs, also known as 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, they inject digestive juices to dissolve the prey and allow it to be more easily consumed.  The adults most likely feed on plant nectar to sustain their energy requirements.

A good question to ask is, why do lightning bugs glow?

There are several theories.  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 lightning bug larvae use their luminescence to warn a potential predator that they taste bad.  Larvae contain defensive chemicals in their bodies.  Then disturbed, larvae also increase their glow's intensity and frequency.

Typical nighttime habitats for adults and larvae take lace 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.  Some Asian species have tracheal gills that enable them to live under water where they feed on aquatic snails.

To attract lightning bugs to your property, reduce or eliminate lawn chemicals.  Add low, over-hanging trees, tall grass and similar vegetation to give adult fireflies a coll place to rest during the day.

Reduce extra lighting on your property because this light interferes with lightning bugs' luminous signals, making it harder to them to locate mates in the area.  Fireflies also determine the time of night they will flash by the intensity of ambient light.  This is why you do not see many lightning bugs flashing on clear nights with a full moon.

Have fun this summer!