Call For a Tow

7. The Threat

By Tom Neale, 7/15/2004

The Threat

All cockroaches have a few things in common that make them dangerous as well as disgusting on your boat. They eat just about anything, including hoses below the water line and electrical insulation. They can cause short circuits, fires, and even sinkings in the right circumstances. They’ve also been known to bite in the night, and they certainly aren’t sanitary. They multiply in astronomical proportions and they don't die easily (if ever). Compton's Encyclopedia reports that female cockroaches typically lay 16 to 45 eggs at a time which take 4 to 12 weeks to hatch. Their success rate is notable; fossils date as far back as 320 million years. Those of us with old boats will not be comforted by the fact that a 300 million year old 4 inch long fossil was found in the Midwest. A female Palmetto bug will produce about 150 young in its lifetime of about a year. The brownish egg cases are purse shaped, around 3/8 inches long, and are either laid loose or glued walls or bulkheads. After the immature cockroach emerges, it takes several months to mature and begin repeating the process.

How do you know that they’re aboard before it’s too late?

Unfortunately, they can be there long before you realize it, multiplying, doing unseen damage, and getting ready to deluge you with hordes. You have a good clue when you turn on the light at night and see a few dozen heading for the bilge, but hopefully you’ll find out far before that. Any little bites taken out of fruit such as apples or oranges should be fair warning. Droppings, scurrying, muted rustling in the night behind liners, munching sounds in the night, mysterious holes in food containers, and actual sightings all call for immediate action. Big cockroaches can make noises so loud and leave droppings so large that the uninitiated may think they’re rats or mice. If you’re setting rat or mouse traps and the bait keeps getting nibbled with no rodents being caught, think “cockroaches.”

Getting rid of them

It helps to ALWAYS keep cockroach hotels or similar products placed around the boat in likely areas. Any dark moist place is a good place for one of these. Don’t place them where a pet or child can get to them. These must be renewed periodically. Follow the directions on the box. Don’t wait until you think you have cockroaches. Keep these in place as preventative maintenance.

Some cruisers use boric acid in powder form, placed around suspect places such as moist warm dark areas. You must be really careful to not put this where pets or children can get to it, or where it will damage any susceptible components. Read directions and warnings carefully. Anything acidic and not intended for the purpose for which you use it can cause more problems than it solves.

You’re, of course, aware of the fumigation sprays or “bug bombs” available in drugstores and grocery stores. These aren’t as effective in boats as they are in houses because boats have so many small hidden tightly contained spaces. If you use these, open up everything you can, and remove as much as you can from below decks. Protect children and pets from residue. Birds are particularly vulnerable to sprays. Others get their boat professionally fumigated. If you do this, be sure that the “professional” is aware of the special issues presented by boats.

Any time you see a cockroach aboard, kill it and throw its body away. Don’t despair and give up the ship, thinking that just because you’ve seen one there must be millions. Often the one that you see, especially if in the daytime, will have just gotten aboard and will not have had time to lay eggs.

To learn ways of keeping cockroaches off the boat in the first place, go to the tips section of for more information.

Copyright 2004-2005 Tom Neale