Custom-Built Homes

By The Old Scot

Do you remember wishing you could wave a magic wand and make something wonderful happen? Of course, we know that there are no magic wands, but quite a number of small insects command a power almost as good. They are able to make plants grow houses for their families, and also stock those houses with nourishing food.

We call these well-stocked habitations “galls.” Galls are abnormal growths, found predominantly on oak and hickory trees, but also on other types of trees and woody plants.

A variety of different insects are responsible for galls, which come in an amazing variety of shapes and sizes. Each configuration, as you might imagine, is characteristic of the type of insect which caused it. Some are hard; some are soft and fleshy. Some are round or oblong, others resemble tops or even tiny vases. Some are smooth, some are rough, while others are covered with hair or spines. Some even look like flowers, while others could easily be mistaken for fruits or even leaves. Some galls are harvested and eaten by humans; others have been a valuable source for hundreds of years of ink and tannic acid for tanning leather.

Let us examine a common gall, the “oak apple”—so called because it is found on oak trees and resembles a little green apple. The outside is a thin, hard rind, but once we cut through that, we find the interior is mostly open space, though dozens of succulent fibers radiate in every direction from the central core out to the rind. Cutting into the juicy central core, we discover inside it a plump little grub. This grub is the larval stage of a gall wasp. It hatched from an egg laid in an oak leaf or twig by the mother wasp—herself hardly more than one-eighth of an inch long.

Before the egg hatched, nothing significant happened to the twig. But when the larva emerged and began feeding, it also began secreting a marvelous substance which in effect took local control of the plant’s growth mechanism. The tree began to grow a house built exactly to the wasp’s specifications.

Let us glance again at the oak apple we have cut open: Truly, a snug house has been arranged for the soft grub! Even if predators bite through the tough rind, they are still far from penetrating the inner hide-away. Furthermore, the grub is literally surrounded by all the food it could ask for.

The grub’s secretion is rich in nucleic acid, which is the key to transferring hereditary characteristics from one generation to the next. One scientific observer said: “It seems probable that the substances injected into plants by insects actually control the growth and division of the plant cells, causing them to develop into special structures. In effect, the insects change the genetics of the surrounding cells, forcing them to form themselves into special habitats.”

Some grubs, after their house is constructed, secrete a different substance, which causes plant starch to be converted into more easily digestible sugar. Sometimes so much sugar is created that the gall exudes sweet honey-dew. In the Southwest United States and Mexico are found honey ants, whose chief food is this honey-dew from galls. Bees in the same region make large quantities of honey from the same substance.

A certain type of aphid—also called “plant lice”—also forms galls, and we could expect a serious problem for adult aphids trying get out and get on with their life cycle. Aphids, you see, have no hard mouth parts, so they cannot cut their way out of their gall homes, as the wasps do. But the aphid’s home is programmed to open its “door” at just the right time to let them out! Somehow, the chemical “blueprint” they secrete causes the gall to develop a slit in its skin, just when the aphids need it.

We may well ask how these insects could develop such powers. Of course, they did not. They can’t, and neither can we. Their bodies have a built-in capability provided by Almighty God. No other answer will suffice. Like so many other special provisions from the One who created the universe, it is impossible that such abilities could be the culmination of one or a million “happy genetic accidents” spread over a million or a billion years.