Yacht Problems: Cockroaches on Board

This article is an adaptation of the material "Hilfe! Kakerlaken an Bord!" by Jens Brambusch for the website Float.de.

Every story has a beginning...

A loud scream seemed to echo through the hull several times, chilling me to the very bones. We were anchored off the coast of Grenada and there was absolutely nothing to suggest trouble, when on a towel in the shower – the very one my girlfriend was reaching for – there was the worst nightmare of her life. Yes, a fat, smug cockroach. Judging by the reaction, the screech had an effect on the cockroach itself – it froze for a couple of seconds, as if in a stupor, and then rushed into the cabin, its paws flashing.

My companion rushed after him with a battle cry, holding a can of poisonous green aerosol in her hand, decorated with a joyful gallery of dead insects. A cloud of insecticide knocks the rough invader off his feet, he slows down and eventually falls doomedly on his back. We slip him a sheet of paper - and overboard with the uninvited guest. Problem solved? Not so.

If you sail in the tropics or subtropics, you will almost certainly encounter cockroaches. And in Europe, especially in ports, they are no longer a rarity. These creatures lie in wait everywhere: in food bags, in the cockpit, even in the tender, or simply crawl from the pier along the mooring lines and fenders. Experienced yachtsmen treat the mooring lines with poisonous sprays - in the tropics they are sold on every corner - or rub them with kerosene.

Sometimes it all starts not even with a cockroach, but with its future descendants - microscopic eggs. They get on board with the sole of a shoe after a walk along the shore, in cardboard egg trays or under paper labels of canned goods. And some species of cockroaches, alas, can also fly. Even if clumsily, but enough to get on a yacht even at anchor.

The best insect killer is a cat

During our four years in the Mediterranean, we were lucky: there were no cockroaches or other vermin on board. Perhaps it was also because we had the best (and most environmentally friendly) parasite exterminator on board from time to time - a cat. One cockroach is not an invasion, but the problem is that they reproduce at an alarming rate.

And they hide in the most inaccessible and dark corners of the ship, where even their four-legged brother would not dare to climb. Cockroaches only need a little moisture to survive, and a yacht is the ideal place: water collects in the hold, and sometimes even ordinary condensation is enough for them.

Don't see the cockroach? It's there!

Cockroaches may not bite or sting, but they are far from harmless neighbors. They carry diseases: from common intestinal infections and salmonellosis to hepatitis. Plus, their excrement can cause eczema and breathing problems. Sometimes these omnivores also gnaw on wiring - supposedly to clean their teeth or simply chew out of hunger, because insulation is often made of organic materials. In any case, you can't joke around with cockroaches on board.

We were lucky: our first cockroach seemed to be a loner. We didn’t notice any new traces in the following days. But, alas, this is not an indicator. Cockroaches are nocturnal and are very good at hiding. All they need is a microcrack, a hole in the hull – and there you have it, a secret refuge. They don’t have a classic nest, but they like warm, dark, damp places where there is food nearby. That is, the galley, the garbage compartment, the toilet, or the same hold.

Hotel for cockroaches

Despite all the precautions - we immediately pour food into plastic jars or vacuum them, leave cardboard on the shore, put shoes in the boat after drying off - every couple of months we still find one or two uninvited guests. Usually in sticky traps that we call "cockroach hotels". We set these traps in lockers and chests. There is little pleasure in this, but there is no panic either. Although anxiety does not leave.

We regularly inspect the boat for traces. Cockroach feces look like coffee grounds - small dark grains, often in the form of tracks. They lay eggs in small capsules similar to cocoons. During molting, cockroaches shed a transparent shell, which remains near their shelter. And, of course, the smell. Yes, cockroaches communicate through pheromones. And it smells... differently: sometimes sickly sweet, sometimes musky, sometimes simply musty and greasy.

You can find cockroaches at the nearest market - the six-legged creatures like to leave their eggs in bunches of fruit.

We have met yachtsmen more than once who had a real cockroach apocalypse. In the worst case, only a professional pest control specialist could help. And that means: disembarking the entire crew for a few days, airing, chemical treatment, then cleaning again. Long, tedious and expensive.

Fascinator bastards

Cockroaches are actually impressive creatures. They are one of the oldest forms of life on Earth, one of the oldest groups of insects on the planet, having lived here for about 300 million years. That means they were running around prehistoric jungles before the dinosaurs. They have survived natural disasters and, according to rumors, even nuclear tests on Bikini Atoll. Scientists have proven that cockroaches can withstand radiation doses ten times higher than those lethal to humans.

In addition, they are absolutely indestructible. Even if you put something a hundred times heavier than them on them, they will not be crushed. Despite their apparent clumsiness, they climb like mountaineers: they have not only claws, but also suction cups, so even on glass or the ceiling - no problem. And they are also incredibly fast. If you compare the length of the body and the speed, then the cockroach will overtake any vertebrate. Even a cheetah. True, only at a good temperature - after all, cockroaches are cold-blooded and become lazy in winter.

Some yachtsmen solve the problem radically - by using salt around the mooring lines. Source: FB-group Sailing Totem.

But no matter how much respect they inspire in biologists, in real life this respect instantly gives way to disgust. Especially when you return after a couple of days on shore - and the first thing you meet on board are not friends, but five cockroaches. We caught them all. But their size surprised us - one was the size of a finger, others were smaller ... and this worried us. It seemed that offspring had hatched on board. We cleaned out all the cupboards - and yes, there was plenty of evidence. We have an invasion.

Boric acid and diatomite

They added more traps to the ones already set up - right in the areas where they found traces. They put a canister of poison on the table in the salon, like a holy amulet. They left the lights on at night, hoping that the cockroaches wouldn't crawl out. 

After the first meeting, we bought boric acid in advance - it can be found in construction stores. In powder form, it fits perfectly along baseboards, under the sink, in cracks. The insect steps on it, smears itself - and dies. There is another method: mix the acid with condensed milk or sweet water, roll balls - and leave in secluded places. But we have a puppy on board, and such "candies" can become too attractive for him. So we decided not to risk it.

Another method that we would gladly use if we had it is diatomite, or powder from fossilized algae. It destroys the insect's protective shell. Natural and effective. But you can't get it in the Cuban marina. Essential oils (mint, lavender, tea tree) also repel a little, but it does not drive out the cockroaches, it just keeps them away for a while. So we put bay leaves in the kitchen cabinets. The hope is not to drive them out, but at least that they will not climb into the food.

One caught - ten alive

Every morning we check the traps. The results are disappointing. The cockroaches are dead, but we know that for every one caught there are at least ten alive. And some say there could be as many as a hundred. So far we haven't seen them during the day - and that's good. Because if the cockroaches start hunting in the light, it means the colony is huge and they don't have enough food.

Luckily, we were lucky with our neighbors. Jörg and Susanna from Magdeburg came to our aid from the side next to us. They have been sailing for a long time, spent many months in Gambia - and know well what cockroach hell is. Almost all the yachtsmen there carried a syringe with them. Not a medical one - with poison.

Gel trap with effect

The product is called Ecogel — a Spanish development. A poisonous gel that cockroaches eat and then carry to their lair. There they infect others, and then they themselves become food for their relatives. And so on — in a chain.

Jörg and Suzanne treated their boats with the exterminating gel and say that after three days the colony had completely disappeared. They left us the remains of the syringe and we, without wasting time, applied the gel in drops: in the lockers, under the refrigerator, along the walls, in the cracks.

Kit young anarchist pest control specialist.

The first results were already in a day. We found dead cockroaches. But no living ones. The nest was never found, but the atmosphere changed. We can sleep peacefully again. And most importantly, turn off the lights in the cabin.

Such gels are the optimal solution for "expelling" cockroaches. Today, you can also find not only such gels, but also improved traps - they look like small plastic containers with such poison, placed in secluded places. The principle of action is the same as that of a regular gel.

In any case, as with other problems on board, it is easier to prevent cockroaches or to expel them from the yacht in time than to fight a huge colony.

New video on Interparus channel

🛠️We tuned and tuned and finally tuned! We present a video review of the Dufour 37 - one of the most interesting boats of the shipyard. As usual, we will tell and show the main modifications, layout and other interesting things. Enjoy watching!

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06.06.2025