New York State IPM Program

Have No Fear: Pests Are Smaller than They Appear

Are subway rats really the size of house cats? Are there American cockroaches or “waterbugs” as big as your hand? Fortunately, neither is true. But a 2012 study offers insight as to why those beliefs exist.

First, some background. Whenever I give a presentation about structural pests, I like to bring some specimens along for show and tell. Invariably, as I open up a box of pinned insect specimens someone says, “I’ve seen cockroaches twice that big!” Outwardly I might act surprised, but that’s because I’m thinking, “Hmm. I’ve been in some sketchy places and seen some nasty things, but the American cockroach is usually about 1.5 inches long, and the average Norway rat is about 16 inches from nose to tail and weighs about 12 ounces.”

Real-world American cockroaches — note their reddish-brown color — measure about 1.5 inches.

Real-world American cockroaches — note their reddish-brown color — measure about 1.5 inches.

Sure, there are exceptions — some can be smaller, others larger, but a three-inch-long cockroach? Surely there’s an explanation.

Then one day I stumbled on a post by ABC News: “Spiders Appear Bigger When You Fear Them” — and it all started to make sense. According to an Ohio State study, being scared can cause an individual to exaggerate the size of the object they fear. A rat racing past you on the subway is sure to induce fear, as is a cockroach in your bathroom. But looking at a dead cockroach, pinned in some entomologist’s specimen box? That’s not so scary.

A challenge: next time you see a critter that would normally make you afraid, take a closer look. You might find that your perception of their size more accurately represents their true size — which in all cases is large enough!

Snout to tail, your average Norway rat is 16 inches long and weighs in at about 12 ounces. Cats? A healthy weight for a small breeds is around 5 pounds; the very largest, 18 pounds.

Snout to tail, your average Norway rat is 16 inches long and weighs in at about 12 ounces. Cats? A healthy weight for a small breeds is around 5 pounds; the very largest, 18 pounds.

 

Author: Matt Frye

An IPM Extension Educator stationed in the Hudson Valley, Matt offers advice, training sessions, workshops and conducts research related to pest management in and around buildings.

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