EXTENSION NOTES: Unforeseen consequences of pest control measures
I once heard about a most unusual case in a small community. I can’t tell you where it is, other than it isn’t too close to us, but it’s not all that far away. Briefly, the people were infested with pests that left them itching and scratching, and the root cause was that the rabbits had nothing to eat.
An early and severe freeze had killed off the flowers, grass and other vegetation, burying it under a heavy load of snow. The rabbits (and probably the deer) began starving. As they are wont to do in such circumstances, they began to eat the bark off the trees. Local orchard owners realized that this would be a catastrophe, as this would kill off their fruit trees. Not only would they have no crops to harvest next year, but they would have to plant new trees and wait nearly a decade for them to get back into production.
They decided the best recourse was to poison the rabbits. This being the early 1960s, I’ve no idea what product they might have been using. Regardless, they spread it around the orchard, and soon, dead rabbits began to be found. Success!
In those days, leash laws were not enforced, and many dogs ran loose in the open country. Dogs being dogs, they ate the dead rabbit\s, and were in turn poisoned by the product consumed by the rabbits. Since the poison bait was working well to protect their trees, the prevailing attitude was to keep poisoning those rabbits ‘til the last dog was dead.
Unfortunately, hawks, owls and other meat-eating fowl also ate the dead rabbits and were in turn poisoned and killed. These birds, known as raptors, are the primary predator of field mice. Without the raptors, the field mouse population exploded. The increased number of rodents devoured any plant material the starving rabbits hadn’t gotten to. With no food, and severe winter weather still permeating the region, the rodents began to move into people’s houses in town.
As you can imagine, the townsfolk were upset with finding vermin in their homes. The city folks began to spread poison bait, just like the farmers had. Whatever they were using was super effective, and killed the mice by the bushel. Unfortunately, house cats ate the dead mice, and the poisoned mice killed the cats.
An interesting thing happens when mammals die. Any parasitic insect pest, like fleas, will leave the body as soon as it begins too cool. The fleas will then attach themselves to any warm body that comes near them. A lack of cats and dogs within this community caused the fleas to migrate onto the humans, causing itchy welts as they tried to make a meal out of their new hosts. The result? The people were scratching all over the street, all because the rabbits had nothing to eat.
In retrospect, a few bales of hay might have kept the rabbits alive and prevented the damage to the trees and the subsequent upset of the ecosystem, but, as someone pointed out, “Humans will pay more to kill you than let you survive.”
This shaggy-dog story is based on a song from folk singer Pete Seeger’s 1966 album “God Bless the Grass.” His song, “The People are Scratching,” is one of the reasons I’m in Extension today.
Larry Caplan is an extension educator-horticulture with the Purdue University Cooperative Extension Service, Vanderburgh County/Southwestern Indiana. You can send email to him at firstname.lastname@example.org.