Aphids are well-known for forming destructive colonies on rose bushes. These minuscule insects pierce a plant's leaves and stems with long, sharp mouthpieces to suck both starch and water. Plants with aphid infestations become wilted and yellowed, and the population may quickly move on to new victims and overrun an entire yard. If aphids have appeared in your garden, it's important to treat them quickly and effectively to reduce the damage.
According to the University of Kentucky College of Agriculture, some plants are more vulnerable to aphids than others. Although many plants survive even with aphid infestations, these vulnerable plants become distorted and malformed, producing damaged flowers and fruit.
Aphids are highly vulnerable to both commercial and homemade sprays. Gardeners who don't want to buy a commercial pesticide, can eliminate aphids with homemade detergent treatments made from 2 tsp. of dish or laundry detergent mixed with warm water in a spray bottle.
Allow the solution to cool significantly before use, then spray the infected plant's leaves, stems and flowers. Concentrate on the undersides of leaves, where aphids generally build their colonies, and look for areas where the aphids are particularly obvious.
The detergent in this solution destroys the aphid's outer protective shell, and leaves the insect vulnerable to predation and dehydration. The detergent solution will also kill aphid larvae.
Other organic alternatives for aphids include spraying the infected plants with water from the hose, alcohol solution or horticultural oils like neem oil or Bt. Predator insects like ladybugs and wasps eat the larvae of aphids, and decimate a population by destroying the reproductive cycle.