It is important to propagate aphids in our fields so the beneficial insects such as lady beetles have something to feed on. It is quite easy to produce a tremendous aphid population which can sustain a large number of beneficials and not be negatively impacted. We just need to give them the right environment.
Here are the easy steps to produce an optimal environment for aphids, which require free nitrates in the plant sap.
Step one, apply more nitrogen then the plants can utilize at the current growth stage.
Step two, do not supply magnesium for better photosynthesis.
Step three, do not apply sulfur the plants needs to produce sulfur-bearing amino acids and complete proteins.
Step four, do not supply molybdenum for the nitrate reductase enzyme.
Step five, do not apply any boron that might boost plant immunity.
If you follow these five very simple steps, you can be sure that your crop will provide the perfect food source for aphids. In addition, it will also be the optimal food source for many other larval insects such as corn rootworm, earworm, corn borer, cabbage looper, tomato hornworm, and others. Really for any larvae. Propagating these larvae provides a ready food source for songbirds and beneficial insects, a valuable ecosystem service.
Of course, if you do not desire to propagate these insects on your crops, the solution is obvious. Do the reverse of the five easy steps, and these insects will not be able to use your plants as a food source.