Posts Tagged ‘Knock Out Gnats’

As the cold recedes from the orange groves and Floridians thaw, the country begins to assess the damage done by freezing weather in the sunshine state.  Though concern is high for the future of fruit, the real blow delivered by the cold snap was to the egos of states far, far away.

Up until now, we thought we had pest problems.  But one look at the iguanas dropping from the trees and our problems seem paltry in comparison.  After all, it’s hard to get pity for a plague of fungus gnats when others are contending with a rain of giant, cold-stunned lizards.   As temperatures plummeted below 40 degrees, the lizards grew comatose, losing their grip on branches.

Yet a pest is a pest, be it large or small, and there’s no need to feel inadequate if what’s bugging you is smaller and less impressive than your neighbor’s.  A closer look at both of these beasts reveals the threats they both pose to our peace of mind.

The Green iguana (Iguana iguana), the Mexican spiny-tailed iguana (Ctenosaura pectinata), and black spiny-tailed iguana (C. similis) in Florida are invasive, non-native animals that escaped from captivity or were released into the wild by people who didn’t want to care for them anymore.  Like any tourist who spends time in the warmth and sun of this subtropical state they thrived, finding mates, raising families, and settling into the landscape.

Fungus gnats (Bradysia species) in Colorado are native insects that are released into the home when people bring potted plants indoors.  Basking in the temperature-controlled climate of a house, fungus gnats breed, fly about, and make themselves comfortable in houseplant soil.

As large plant eaters, iguanas pose problems for landscape plants, gnawing on trees, shrubs, and ornamentals like it’s an all-you-can-eat buffet.   After their meals, they enjoy lazing in the sun on sidewalk, stone walls, and other flat stone surfaces, where their droppings collect in an unsightly, smelling mess.

Fungus gnats are dainty eaters, preferring to dine on soft algae, fungi or decomposing plant parts in houseplant soil.  Occasionally they nibble plant roots, but are rarely problems for plant health.  Egg to adult takes a mere three weeks, at which point the adults fly free from the soil and spend a week (or 10 days) looking for love, laying eggs, and driving homeowners crazy.

As iguanas have become entrenched in Florida, alarm has risen over their increasing numbers and damage to yards.  But control is difficult.  These lizards bite and scratch to defend themselves, but it’s their tail you have to watch:  a blow from this mighty muscle is a slap you’ll never forget.

Here’s where fungus gnats measure up to their larger competitor.   Flying lazily about the room, the gnats seem drawn to human faces, setting the people to flailing their arms to drive off the insect.  Often the attempts at swattage end in tragedy, when an innocent bystander – family member, friend or pet – is smacked by the wildly waving hands.

Exclusion with strong screens may keep iguanas at bay and using plants they don’t like to eat will have them looking elsewhere for fodder.  Experts recommend accessorizing trees with sheet metal to stop iguanas from climbing, cementing in their burrows, or encouraging beneficial predators like raccoons, vultures, or feral pigs.  Of note is that experts draw the line at shooting iguanas, since discharging firearms in areas where people live is frowned upon.  Slingshots are encouraged as a harassment tool, provided you’re careful to have a solid backstop.

Fungus gnats can be a mighty big problem to overcome.  But because they are a bigger problem in homes where houseplants are overwatered, try allowing the soil to dry between watering.  In general, the gnats live in the top two inches of soil; letting the soil dry in this area kills eggs and larvae. 

There are several pesticides with pyrethroids available for those who would like a stronger control.  Look for those that are persistent, active for several days after application.  Or, if you prefer, Bacillus thuringiensis strain israelensis (Bti) is helpful when applied as a soil drench when you water.  But Bt is tough to find as a homeowner.  Try searching for Gnatrol or Knock Out Gnats.

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