The difference between migrating, hibernating and traditions

Published 4:50 pm Friday, December 6, 2019

The critters are congregating in the southwest corner of the white ceiling above the pale yellow walls in the small room that is mostly windows. They prefer light colors. 

Most houses have their ladybug traditions and mine takes place in the spot I call a sunroom. 

For several weeks now, ladybugs have snuck in, gathered in their traditional corner and mostly died and dropped to the floor. I’m not a neat freak, so an occasional sweep up of dead bugs constitutes ladybug management for me.

Sign up for The Vicksburg Post's free newsletter

Receive daily headlines and obituaries

The few crawling the walls and window casings are left alone because the poor souls are eventually going to give up and die too.

Over the years we’ve heard the fall massing and movement of ladybugs referred to as migration or hibernation or both.

Just for the fun of it, and because there is nothing new to say about household ladybugs, I’m going to attempt to show both terms are technically incorrect.

Animals that seasonally migrate travel long distances between areas with significant climate differences. Some migration is for protection from weather extremes. Some are because food supplies change with weather and some are for the climatic effect on reproduction, be it mating, birth or rearing young. 

There are indeed insect species that migrate. 

Monarch butterflies are probably the best-known migrators that live here part-time. The entire butterfly and moth group, the Lepidoptera, includes the most species of bug migrators, but there are others in the insect world. 

We used to say some of the worst crop-damaging insects of local crops such as soybean loopers migrate here every year since the species rarely survive the winter this far north. But theirs is not true migration. There is no return trip southward by any life stage of the loopers. They all die here in winter. 

Reproduction takes place next spring in south Texas and Mexico where their local loopers survived the winter. As those new generations multiply, the offspring’s offspring eventually spread this far north the next summer.

Our local ladybugs don’t migrate. They hunker down nearby for the winter unless you want to claim them crawling across the neighbor’s yard to your house is migration. It’s not.

Numerous layman stories and reports on ladybugs use the word “hibernate” to refer to their winter inactivity. The correct term is “diapause.” Bears hibernate. 

Most insect species go into diapause to deal with any big-time stress, be it extreme cold, drought or a shortage of food. Diapause is a state of reduced activity and body functions. 

I’m not up on insect brainwaves, but diapause is more of a psychological state than a physical one. Folks who study such tell us monarch butterflies are actually in diapause during their long migration flight.

A final word on ladybugs: that yellowish stain they sometimes leave behind comes from a liquid secreted through their leg joints and its purpose is to smell so bad and taste so bad no predator would want to eat them.

 

Terry Rector writes for the Warren County Soil and Water Conservation District.