Eggshells make a great organic pesticide. The best way to use them is to simply crush them into small pieces or grind them into powder using a food processor. Sprinkle them on and around flowers and vegetables.
Fleas live all year in Central Texas but are especially a problem in the summer months. Aphids are another problem for gardeners. They suck the juices out of the plants causing dehydration. They also attract ants. Eggshells will keep beetles out of the garden as well.
Not only will eggshells keep pest out of the garden, but they will add calcium to the soil. Calcium will promote healthy cell walls and membranes in the plants and add porosity to the soil allowing better water penetration.
Using eggshells as pesticide is eco-friendly and much cheaper than commercial pesticides.