Parasitic Insects and Evolution

Would God really want to take credit for the mosquito? Natural theology, which reigned before Charles Darwin introduced his theory of evolution, argued that creation demonstrated the power, wisdom, and goodness of God. But what about nature’s evils? Consider for example the ichneumonoidea, wasps that inject their eggs into a host insect. They also inject a chemical that paralyzes the host without killing it. Aside from providing an incubator for the wasp’s eggs, the host also becomes the first meal for the newly hatched wasp, which carefully consumes the host so as to keep it alive a long as possible. As is so often observed in nature, profound levels of evil are accompanied by profound levels of complexity. Evil, it turns out, is not always banal.

The parasitic wasp

In Darwin’s day the entomologist (and Reverend) William Kirby pointed out the amazing complexities of such parasites. How did the parasitic wasp know how to avoid injuring the vital organs? He wrote:

In this strange and apparently cruel operation one circumstance is truly remarkable. The larva of the Ichneumon, though every day, perhaps for months, it gnaws the inside of the caterpillar, and though at last it has devoured almost every part of it except the skin and intestines, carefully all this time it avoids injuring the vital organs, as if aware that its own existence depends on that of the insect upon which it preys!

But Kirby’s views were not shared by those who felt god would never create such a horrifying world. Centuries earlier Thomas Burnett, Ralph Cudworth, John Ray and others had called for a distancing of God at the sight of far less wrenching evils. Imagine what their response would have been to nature’s new round of atrocities being uncovered by science.

It probably would have been similar to Darwin’s response, who argued in his book on evolution that the instinctive hatred of the queen-bee for her own fertile daughters and the parasitic wasp feeding within the living bodies of caterpillars were yet more proofs for his new theory. It seemed that Darwin was, as one historian put it, “yearning after a better God than God.” As Darwin wrote to Asa Gray in 1860:

I own that I cannot see as plainly as others do, and as I should wish to do, evidence of design and beneficence on all sides of us. There seems to me too much misery in the world. I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of caterpillars, or the cat should play with mice.

Science and religion were “thoroughly interwoven in Darwin’s life and thought,” but this was hardly unique to Darwin. It is not surprising that many theologians gave a warm welcome to Darwin’s theory. Nor is it surprising that Darwin’s theory would lend itself to a new round of theological naturalism. Theological naturalism had argued for a distancing of the Creator from creation. Now Darwin’s theory was filling in the details. It was natural selection, not a divine finger, that did the job. Darwin’s idea provided a new framework for continued theological speculation.

The mosquito

More disgusting than the parasitic wasp is the mosquito, which brings misery and death to hundreds of millions of people every year. As evolutionist Ken Miller rhetorically asks, would god really want to take credit for the mosquito? Of course if Burnett, Darwin, Miller and the rest don’t believe god would create such evils, then evolution must be true, one way or another.

But like the parasitic wasp, the mosquito is complex. For instance, a few years ago Chinese researchers discovered that mosquitoes have an amazing ability to land, walk and take-off from water. Of course mosquitoes are not the only insect that can move about on the water’s surface, but the buoyancy of a mosquito’s leg—about 23 times the mosquito’s body weight—and its nanostructures are remarkable.

Blood-feeding insects also have exquisitely designed carbon dioxide sensors to home in on their prey. Research has identified two dedicated neural receptors that together cause nerve signals to be sent when carbon dioxide is present. The experiments found that the presence of both receptors is required—either one alone failed to sense the carbon dioxide.

As one scientist explained, such molecular sensor systems are “exquisitely sensitive” to carbon dioxide levels we don’t even notice. They are, indeed, “wonders of natural engineering.”

Given such an exquisite design, and given that both receptors are required because a single receptor working alone is ineffective, one might think that evolutionists might struggle to explain this engineering marvel.

But evolutionists have no such problem. After all, would god really want to take credit for the mosquito?