Vacuum and soap kill insects on plants.

A single chrysanthemum harboring a few insect eggs can infest a greenhouse with clouds of tiny, gnat-like white flies in a few days. The common remedy is an expensive, unpleasant schedule of spraying with potent pesticides.

Horticulturists Durward Smith and Jay Fitzgerald and biosystems engineer George Meyer, University of Nebraska-Lincoln, have a different idea. They eliminate pesticides by combining vacuum infiltration with soap solutions to kill white flies and aphids, two of the most common greenhouse pests. Their method literally blows insects up like balloons and pops them.

Smith submerged a chrysanthemum stem into a soap solution, placed it in a vacuum chamber, and created a vacuum. "A good part of an insect's body is filled with gas. The vacuum draws out all this gas," he explains. When the vacuum is released, the solution rushes in to fill all the insect's cavities. The insect expands until it ruptures.

The scientists tested chrysanthemum and poinsettia cuttings infested with insects at different vacuums for different lengths of time. After treatment, they examined cuttings under a microscope to determine how many insects died. They found the most effective method was vacuum infusion of a soap at an absolute pressure of 30.5 cm of mercury for three minutes. This killed the eggs of greenhouse white flies and red potato aphids, as well as their immature and adult stages.

The plant undergoes the same process of cell expansion as the insects, but plant cells are more elastic and don't...