Red Aphids

“Aphids are called ant cows because ants herd and ‘milk’ them to secrete a substance called honeydew!”

Summary

Aphids are parasitic insects that target plants. They suck the sap out, draining the plant and making it less resistant to other pests and diseases. Aphids come in many colors, such as green, black, yellow, red, white, or black depending on the type of plants they feed upon. Aphids produce a substance called “honeydew,” a sugary liquid loved by ants.

Scientific Name and Types

Aphids belong to the superfamily Aphidoidea and the order Hemiptera, and so are related to cicadas and bed bugs. They are known by other names such as plant louse, ant cow, and greenfly. Aphids are called ant cows because ants keep them in sizeable herds in order to milk their honeydew, a substance secreted through their anus. In exchange for this sugary food, ants guard aphids and shepherd them to new host plants when the old one becomes uninhabitable.

The genus Uroleucon contains 226 species distributed across the world. Uroleucon contains many red, reddish-brown, and blackish-brown aphids. Some of the red aphids that belong to this genus are:

1. Red Yarrow aphid – Uroleucon achilleae
2. New England aster aphid – Uroleucon ambrosiae
3. Harebell aphid – Uroleucon campanulae
4. Oriental lettuce aphid – Uroleucon formosanum
5. Red goldenrod aphid – Uroleucon nigrotuberculatum
6. Dusky-tailed sunflower aphid – Uroleucon obscuricaudatum 
7. Wild lettuce aphid – Uroleucon pseudambrosiae
8. Goldenglow aphid – Dactynotus rudbeckiae
9. Crimson tansy aphid – Uroleucon tanacetii

Many other species of aphids vary in shades of red, ranging from red to reddish-brown. Here are a few of them:

1. Campion aphid – Brachycaudus lychnidis
2. Chrysanthemum aphid – Macrosiphoniella sanborni
3. Ivy aphid – Aphis hederae
4. Rose aphid – Macrosiphum rosae
5. Variegated Oak aphid – Lachnus roboris
6. Rosy apple aphid – Dysaphis plantaginea
7. Plum thistle aphid – Brachycaudus cardui
8. Common Periphyllus aphid – Periphyllus testudinaceus

Appearance

Aphids are tiny soft-bodied bugs with antennae and compound eyes. They average from one-eighth to one-sixth of an inch in size and are pear-shaped. Aphids weigh a modest two-tenths of a milligram on average. About 12 aphids weigh the same as a mosquito! Aphids are not invisible to the human eye, but they are so small they can be hard to spot.

They have six legs and long tubes called stylets, which they use to feed on plant sap. Most aphids have tubes on their abdomens called cornicles. These tubes secrete a liquid called cornicle wax when they are threatened. The giant willow (Tuberolachnus salignus), which grows up to two-tenths of an inch long, is the largest aphid. These insects live in colonies on the leaves of host plants. Some aphids are eusocial, which means they have highly organized social structures.

Habitat

Aphids populate most landmasses on Earth. They prefer temperate regions to tropical and colder regions. About 5000 species of aphids live across the globe. They are found mostly in temperate zones. For just about every species of plant, there is at least one species of aphid that damages it. About 1,350 species reside in the United States and Canada alone, which is about 27% of the total known species of aphids. Aphids generally live on the leaves of host plants. They prefer the underside to the top. There, they live in large colonies, feeding off of the plant sap until it gets overcrowded or the plant begins to wilt from exceeding loss of nutrients.

Aphids travel long distances by means of winds, a process known as passive dispersal. Aphid activity decreases with a rise in temperature. They are most active in springtime, and that activity wanes once summer rolls in.

Life Cycle and Reproduction

The life cycle of aphids is between one week and 40 days. Wingless females reproduce via parthenogenesis. They can give birth to 12 nymphs a day. These wingless female offspring called nymphs are sometimes already pregnant! These nymphs give birth to more nymphs, and this cycle repeats itself.

When the host plant becomes uninhabitable or overcrowded, some species of aphids produce winged spawn that go off in search of another host plant. Some adults also sprout wings in these dire situations. However, aphids are not strong fliers and lose their wings after a few days. They have a relatively short lifespan of 20-40 days.

Diet

Unlike bed bugs (Cimex lectularius and C. hemipterus), which feed on blood, aphids only drink plant sap, which means these critters won’t bite you.

The adult aphids, usually winged, probe the plant to make sure it is eatable. Then, they release their saliva into the plant and taste its sap. By doing so, aphids may introduce viruses to the plant. If the plant is deemed unfit to host the new colony, the insects will abandon it. Most aphids feed only on one or two plant species, but some feed on hundreds of plants throughout the year.

Uroleucon aphids predominantly feed on one or a few species belonging to the daisy (Asteraceae) and bellflower (Campanulaceae) families.

Aphids do not pose economic problems other than ruining commercial crops. Usually, aphid colonies don’t do much damage, but in large colonies they can inflict substantial damage. They are plant disease vectors, transmitting harmful viruses to plants and eventually killing them. Soybean aphids, for example, cause crop yield losses of 10-15% in the midwestern United States each year. Red aphids also target tobacco crops.

Prevention and Control

About 450 out of 5,000 species of aphids are pests to food and commercial crops. They carry diseases from plant to plant and infect a new plant when they deposit their saliva into it. They also drain plants of their nutrients and leave them wilted, withered, and useless. Their honeydew deposits sheathe the plant’s leaves, attracting mold, preventing photosynthesis, and killing the plant.

There are many ways to control aphid populations in your garden. There are biological ways which employ natural means, and then there are chemical ways. Gardeners should try controlling these pests by biological means first before using chemicals so as to not harm the other beneficial insects in your garden. Also, aphids can grow resistant to the chemicals used to kill them. Besides, spraying your plants with pesticides won’t do the aphids that much harm since they mostly live on the underside of leaves. However, spraying a mixture of water and soap directly underneath the leaves is a common method of getting rid of these pests. Although this is an effective method, it could potentially negatively affect the plant as well.

Introducing aphids’ natural predators such as ladybugs and lacewings is another biological method. Predators may also include certain passerine birds, and even some fungi like Lecanicillium lecanii or Beauveria bassiana, which are toxic to aphids.

Related Animals

• Cicadas
• Weevils
• Bedbugs