Rainy Season is Roach Season. Here’s What to Do.

A cockroach at a home in Bangkok.

BANGKOK — The antennae come first, peeking from the bathroom drain. Seeking.

Then the rounded head, shiny brown carapace and hairy legs emerge to start feeling out the tiles, oblivious to the human screams.

Ah yes, the cockroaches have come. Feeding off human filth and terror, their determination seems almost sadistic. Let’s not even talk about when they fly into your face.

Exterminators and experts alike confirm that the rainy season brings more of them boiling from the shadows. Do not despair. There are ways to manage these vilified insects if they’re making life gross.


Managing Your Mass Murder

Two main types of roaches roam Thai domiciles: the American variety – larger ones that can fly and inhabit trash piles and sewers – and German cockroaches, the smaller ones that are ridiculously immune to chemical warfare, according to Thanawut Phaiphetnoi of Minibug exterminators.

The two do not live together – unless your home is an infested disaster, in which case please stop reading and find a new home. It’s the German roach that is so very difficult to kill, Thanawut explained.

“German cockroaches are the hardest to get rid of, but if we can get rid of them, there’s no species in the world that’s unexterminatable,” Thanawut said.

Just give them a good stomp? Good job, you’ve just spread baby roaches everywhere.

“Crushing them with your foot is the wrong way to kill them,” the 42-year-old exterminator insisted. “The German females will have up to 23 eggs in their body. Even if you crush her, the larvae aren’t dead yet.”

Instead, Thanawut recommends, set off chemical bug bombs or pour boiling water onto the pests. If you find yourself enjoying the latter too much, seek professional help. Or pro help: Thanawut’s company uses special chemicals that attaches microcapsules to the bugs, killing them within 30 minutes and spreading to their spawn.

Using bug bombs, usually laced with the insecticide bifenthrin, is only good for killing those in the immediate vicinity but won’t affect their nests. Roach traps, such as off-the-shelf Hoi Hoi Cockroach Homes, usually use glue to trap or dry bait to kill roaches by affecting their nervous systems. He says they’re only good for monitoring how many cockroaches you have.

“We exterminators only use traps to monitor how many cockroaches are in an area. They spread so fast, growing mature in seven days. Traps only help to an extent,” Thanawut said.

If you’re not using a professional exterminator service like Thanawut’s, the professional bug slayer suggests Bayer’s Maxforce Forte gel to massacre the bugs like a real Starship Trooper.

“It’s a syringe where you paste the gel, or cockroach food about as big as a matchstick head. Then cockroaches eat it and slowly die from the poison, usually when they get back to their nest. Then, other cockroaches eat the corpse and die,” Thanawut said.

This daisy-chain of death is only available wholesale. Here is a list of distributors to contact.

But don’t worry, there’s a natural option that may be just as effective as regular traps.

“But if you’re looking for a chao baan [homespun] way to kill them, get a bowl of very oily palo soup,” he said, referring to the pork-and-egg Chinese five-spice savory dish. “Wipe the edge of the dish with lots of vegetable oil. They will go in to drink the oily soup and fall in, and can’t climb out because of the slippery edge.”

Raining Roaches

The current rainy season brings not only floods but also an influx of scuttling nasties into homes, according to a domestic science professor.

“Rainwater rushes through sewers and drains, pushing out cockroaches,” said Duangruthai Thumrongchote, dean of home economics tech at Rajamangala University of Technology Krungthep. “Where do they go from then? Well, they still love to be near water, so they will find dark, musty places in your homes to stay.”

He said cockroach nests disturbed by rain explode, leaving the insects to find new homes in cupboards and musty kitchen areas, even hiding within ceilings so they can be near food sources.

Prevention is the best cure, Duangruthai insists.


Duangruthai recommended that all food sources for cockroaches, such as open trash, be cleaned and removed from the home as quickly as possible. He said paneled ceilings are also an opening for cockroaches and tiny holes must be plugged.

“They are so hard to kill. It’s better to prevent them. Cockroaches dislike cleanliness, so make sure your house is spotless,” she said. “Notice your bedroom and open-air spaces have less roaches than the kitchen.”

“If there’s no food sources, they will migrate,” the professor said.