All energy enters the food system through plants. They are the “primary producers.” Everything else depends on their work either directly or indirectly. Cows eat grass and we eat cows. The biomass, that is the total mass of individuals, tends to decrease as one moves upwards in the food chain. That is if we could weigh all the plants in an ecosystem they would weigh more than the things that eat them.
This does not always seem immediately true to me when I turn the soil in the spring and find the grubs. “Grub” can mean “food” and it can mean “to dig about in the soil.” But the grubs that live in my soil inhabit the word better than those other meanings. Their pale translucent skin, foul little legs and puckered brown head equipped with horrific mandibles that have evolved for the express purpose of eating plant roots look like grubs. When I find them they tend to be curled up looking innocent. I am not fooled. To my chickens they look like little protein packets.
But a grub is neither disgusting, nor a protein packet. A grub is the larval form of a beetle. Beetles, flies, ants/bees and moths/butterflies all go through complete metamorphosis. That is they hatch from an egg as a larva which spends its time feeding (hungry caterpillar). Maggots, caterpillars, and grubs are all larva. We don’t usually see bee and ant larvae but they’re kind of grub like. The larvae then pupate (form a pupa) from which they emerge as an adult that looks little like the larva.
So these grubs are just wee little baby beetles crawling about under the soil eating roots. Yet we spend enormous amounts of money in this country ridding our lawns and golf courses of grubs. Of course chickens aren’t the only ones who look at grubs as food: skunks, birds and moles all eat them. I’m sure they’re quite delicious and as they are just one remove from the primary producers there are a lot of them.
A neighbor recently asked me the identity of some grubs and I was forced to plead ignorance. After some hunting I found an excellent resource on the UMass extension website: http://extension.umass.edu/turf/fact-sheets/white-grub-identification. The best way to distinguish grubs from one another is by focusing on their anal slit. This takes practice apparently, so I’ve gone ahead and penciled in the weekend for some solid grub anal slit pondering.
After pupation grubs turn into various kinds of beetles. We see lots of june bugs and Japanese beetles in the summer and many of our grubs will turn into these. They are pests both as larvae and as adults.
Franz Kafka’s “Metamorphosis” begins “One morning, when Gregor Samsa woke from troubled dreams, he found himself transformed in his bed into a horrible vermin.” I think “horrible vermin” paints it on a bit thick, but if Gregor had changed into a vermin, does this not make the human a larva? Perhaps each night we lay down hoping to metamorphose into our more perfect selves. We’re probably enormous dung beetle larva: grubs.