Arrogant mice and humble bees

Bill Meredith

Among the visitors to our yard this summer were two that most people would not welcome. One has been a problem; the other, related to it in a peculiar way, has been a source of pleasant reflection.

The problem actually arrived last winter. After a light snowfall melted, I was walking in the yard and noticed that a trail had been created in the grass where field mice had made a tunnel under the snow. Such things are not unusual, and I thought little of it at the time; but as spring began, there were ominous signs on the horizon. The new snapdragons and pansies we set out in the flowerbed disappeared, gnawed off at ground level. Chrysanthemums and four-o’clocks that had survived the past several winters also were missing. Gladioli and daffodils sprouted, were bitten off, and sprouted again, to no avail. Things were getting serious.

At first I suspected deer and rabbits were the culprits; both had left tracks all over the yard whenever it snowed throughout the winter. However, there were no deer tracks at the scene of the crime in the flower beds, and rabbits often had nested among the various plantings without eating them in the past; so my suspicions were directed elsewhere. Finally, one evening in May when I was sitting on the porch with the crossword, a mouse darted across the sidewalk and disappeared into the adjacent flowerbed; and I recalled the tunnels under the snow from months earlier.

My grandmother always said that if you see one mouse, there are sure to be more, and she was right. Within a few days I began to notice flashes of dark fur darting about in the flowerbed on the bank across from the kitchen window. Next I discovered a winding path through the lawn from that flowerbed to the one by the porch; it was a well-worn runway two inches wide, and the grass arched over and concealed it from sight. Watching from the porch I could see the grass wave like a wheatfield in the wind whenever a mouse went by.

The first couple of times I saw them, I jumped up and ran out into the yard with vague intentions of stepping on them, but they were much less arthritic than I; the tunnel in the grass was empty by the time I got there. My wife, always favoring the direct approach, suggested setting snap traps throughout the lawn and flowerbeds; I managed to convince her we would catch more birds than mice by that method. So for the next month or so I spent my evenings on the porch with an air-powered pellet pistol instead of the crossword in my lap, blazing away like a rancher protecting his herd from wolves. The mice recognized the absurdity of this long before I did; every evening at 4:30 they would start coming out into a bare spot on the bank, where they would sit up on their hind legs like squirrels and laugh at me before grabbing the nearest green object. One in particular had the same expression on its face as the golf course attendant who once parked his mower squarely in the center of the fairway and motioned for me to go ahead and tee off, secure in the knowledge that he was in the safest place on the course. From 25 feet away with the air pistol, the closest I ever came to hitting one of them was about 3 inches; it sneered disdainfully at me before ambling back to shelter. Eventually my wife took matters in hand and spread DeCon around the various runways, and soon the mouse population declined.

Technically, they are not mice, but meadow voles (Microtus pennsylvanicus), big headed, short tailed, with small, beady eyes and short ears. They may live as long as 3 years, and reproduce the year round. A new litter arrives about once a month; one particularly hyperactive female in captivity produced 17 litters in a year. Average litters have 3-5 young, but sometimes there are as many as 9. Their populations fluctuate in cycles; the first half of this summer favored them, but the drought we have experienced lately has probably had as much effect as my wife’s DeCon. Both they and the flowers are no longer in evidence.

I noticed the other visitor while trying to ambush the mice; it was a large bumblebee that hung around the front porch late in the spring. Normally I would not have paid it much attention, but the newspapers had just run a story about bee populations in Maryland being destroyed by parasitic mites, thus raising concerns about crop pollination; and we had just planted our squash and cucumbers. So the bee was of interest. As I watched it buzz around the porch one day, it disappeared into the myrtle and lily-of-the-valley, which were not blooming at the time; and by watching more closely I found it had gone into a hole dug under the porch steps by a chipmunk last fall.

In the early spring, all of the bumblebees you meet are queens. They mated with drones the previous fall, and spent the winter in hibernation; they are young, fertile, and impatient to start families. They find a suitable hideout and make a honeypot or simple comb consisting of only a few cells, more the shape of a paper wasp’s nest than a regular honeybee’s comb, and begin laying eggs. At first, the queen has to forage for nectar and pollen in addition to laying eggs and tending the young, and the labor takes its toll; most of the fur gets worn off her body. The young ones all hatch into sterile worker females, however, and soon they are doing most of the foraging; the comb gets larger, and the old queen spends more of her time resting and laying eggs. Just before she dies in the fall, she lays some unfertilized eggs which hatch into drones; they mate with the youngest workers, who become next year’s queens.

In England, these insects used to be called Humble Bees, and they were the stuff of which legends were made. In The Origin of Species, Charles Darwin related a story that asserted that old maids were the real power behind the British Empire. The reasoning behind this remarkable claim was that the British army lived on beef; to raise beef you must have clover; and clover, particularly red clover, is pollinated only by humble bees. When field mice are abundant, they often break into the nests of humble bees to steal the honey pots, thus killing the bees. Old maids keep cats, and cats kill mice; hence the bee population, the clover crop, and the beef supply all depend on the number of old maids— well, you get the idea. It’s the food chain in action again.