Aphids (Homoptera Aphididae) also known as plant lice are tiny (1/8″) soft bodied, oval to pear shape insects that come in green, pink, red, brown, black or dusty gray. The woolly apple aphid has a fluffy white cottony coating that closely resembles a mealybug. They congregate in groups and feed on the plant juices of young leaves, succulent tip growth and flower buds causing curling, stunted and distorted leaves. Infested leaves can wilt in bright sunlight and turn yellow/brown. The whole plant can turn pale yellow and stop growing. For infestation, check new growth, stems and underside of the leaves.
Root aphids attack plant roots and display similar symptoms.

aphids on mandevilla plant
Aphids excrete honeydew which attracts ants and is the perfect medium for black, sooty mold fungus. In addition, they can also transmit incurable viral diseases. Most damage occurs when temperatures are 65-80F degrees.

aphids on basil

Aphids develop from an egg to adult and also give birth to mature insects that reproduce rapidly.
Each adult aphid can produce 80 offspring within a week. Some mature adults have wings and fly,  infecting other plants.

Aphid control:

A strong water spray will wash them off the plant, repeat at least 3 times. Handpicking, by squeezing the bugs between your fingers will help reduce the population. Yellow sticky traps will attract and control aphids.

Homemade sprays such as garlic spray and hot pepper spray will repel the insect.
Garlic spray: Mix 1/2 cup of finely chopped garlic cloves with 1 pint of water, strain and spray.
Hot pepper spray: Mix 1/2 cup of finely chopped or ground hot peppers in 1 pint of water, strain and spray. Use gloves to protect your skin.

If that doesn’t work use insecticidal soap every 3-5 days for two weeks.  Do not use insecticidal soap on gardenia. A stronger alternative is pyrethrum/ alcohol spray: combine 1 TBS alcohol to 1 pint of pyrethrum. The solution should have direct contact with the aphids to be effective. Other chemical remedies such as Neem are available. Be sure to follow label directions for safe application on specific plants.

Natural predators such as ladybugs, parasitic wasps, syphrid fly larvae and green lacewing larvae are biological controls that feed on aphids. They reduce the population and can eliminate the need for treatment when present. Aphids are also susceptible to fungal disease in humid weather. Look for reddish or brown, shriveled dead aphids