Root Aphids

Root aphids that live above or at the soil line are members of the Phylloxera family and are near-cousins of aphids. Unfortunately, they are an escalating problem, particularly among indoor growers. In addition, they are spreading fast to regions where they previously did not occur.

Unlike green aphids, they are hard to spot on stems and leaves, so there is a bigger chance they can get out of control. In addition, they multiply rapidly and suck up copious amounts of sap, depleting the plant’s vigor and eventually killing them.

Root Aphid Scientific Name

Root aphids belong to the order Hemiptera, a diverse group of insects that vary in shape, color, and size. This order consists of 6000 species and ranges in size from 0,04 to 4.3 inches. Hemiptera means “half wing,” and their common features include 2 sets of wings. However, some species are wingless, and others only have forewings.

Some species have hardened wings at the base, but most have membranous wings. In addition, they have sharpened mouthparts that pierce plants and suck out the sap; these piercing appendages are often referred to as proboscis or rostrums and extend from underneath the head.

Hemipteran’s offspring resemble adults but are smaller. They are often mistaken for beetles; however, root aphids are distinguished by their mouthparts, which are sharp and pointed, while beetles have mandibulate.

They are members of the Aphididae family, which consists of small, soft-bodied insects. Similar characteristics include two little tubes protruding from the end of the abdomen called cornicles. In addition, they have small eyes and piercing mouthparts.

They come in various colors, from green to black, to brown, to red, and have long antennae. Aphididae move incredibly slowly. In fact, they barely move at all.

Because there are so many species of root aphids, there are many different scientific names; some species include:

Rice Root Aphid (Rhopalosiphum ruiabdominalis)

Rice root aphids are native to North America and can survive outdoors all year long. They are considered major pests because they negatively affect plants that grow in soil and hydroponic systems. In addition, they differ from other aphid species due to their life cycle that entirely takes place underground, which makes it harder to recognize an infestation.

While they can reproduce throughout the year, they can only stay alive for a few days without feeding on a host. In addition, they don’t lay eggs but give birth to live offspring.

Corn Root Aphid (Anuraphis maidi radicis)

The corn root aphid is very similar to woolly aphids because they suck sap from plants and leave behind a waxy substance called honeydew.

This substance can become moldy, causing the tops of plants to turn black and giving off a sooty appearance. While they mainly infest cultivated grasses like corn, they also attack grassy-type weeds.

These aphids are blueish-green or gray, have soft bodies, and have a spherical shape. They are tiny, only measuring 1/16 inches in length. They reproduce, on average, 9 generations a year, and unlike most insects, they give live birth.

Hawthrone-Carrot Aphids (Dysaphis crataegi)

Hawthrone-carrot aphids are small insects, only measuring 0.08 inches long on their primary hosts. They have short antennae, and their coloring varies from green to gray, dusted with wax particles.

The wingless females have a yellow-gray or green-gray coloring on their secondary host and are dusted with fine wax particles. However, winged viviparous females are reddish-gray color with black markings, while egg-laying females are red with black markings.

Tulip Bulbs Aphids (Dysaphis tulipae)

Tulip aphids are tiny pale to dark green insects with medium to long darkened cornicles. Because they prefer to feed on tulip bulbs, they are often referred to as tulip bulb aphids.

They also infest shoots, leaves, buds, and flowers after they have started to grow. Unfortunately, they are detrimental to these plants because they can transmit the tulip-breaking virus and yellow streak virus in the landscape. In addition, these aphids give birth to live nymphs that slowly mature into winged or wingless adults.

Root Aphid Appearance

Root aphids range in color from white to whitish-yellow or brown. They look very similar to aphid species found on new stems and leaves. However, they are pear-shaped and have shorter legs and antennae.

Most root aphid species have pipes penetrating from underneath the abdomen and pointed sharpened mouthparts, which they use for extracting sap from underground bulbs, roots, and rhizomes.

In addition, later in their life cycle, they secrete a white, waxy substance that covers their bodies and also leaves a trail as they move across the host.

People often confuse them for mealybugs, who also cover their bodies in a white, threadlike substance. However, root aphids are tiny insects that only measure around 0.09 inches long.

Root Aphid Behavior

These aphids burrow into the root of plants, often creating scars on the leaves, which makes them susceptible to mildew and various diseases. As the infestation grows, root aphids will crawl up to the stem to feed.

Once they have sucked the plant dry, they will sprout wings which help them to fly to new plants ready for the plucking.

Root Aphid Habitat

As their name suggests, these aphids primarily feed on the roots of plants, particularly rice plants. However, their hosts have significantly changed as their populations have moved to various geographic regions. They now feed on crops like:

• Tomatoes
• Cereal
• Potatoes
• Peppers
• Cannabis

Root Aphid Diet

Root aphids feed on plants like coreopsis, veronica, aster, and sedum. In addition, they like herbs like basil and oregano. But their diets do depend on their geographical range.

Root Aphid Predators and Threats

Root aphids have many predators, and they will vary depending on the habitat; however, some predators include:

• Birds
• Ladybugs
• Wasps

The only threat to root aphids are humans trying to eliminate infestations. However, because of their high reproduction rate, their population numbers are not under any threat.

Root Aphid Life Cycle

Root aphids’ life cycle consists of three stages, which include:

The Nymph Stage

Nymphs take 9 to 10 days on average to mature, with a complete lifespan of an estimated 30 days. Depending on the species, they have 6 to 8 legs that measure between 0.04 to 0.08 inches.

During the nymph phase, there are 4 stages of development. They tend to gravitate to the plant’s root system. The nymphs are relatively slow crawlers but can quickly move from plant to plant through growing medium debris, water passing through drainage holes in potted plants, and dirty grow equipment.

The Wingless Adult Stage

Wingless adults spend their developmental stage on the roots of plants and can measure up to 0.12 inches long. They reproduce asexually in enclosed cultivation areas and can produce multiple new offspring daily.

While males are produced, female root aphids give live birth to genetically similar female aphids. They reproduce so fast that their population numbers can double every 1.5 days!

The Winged Adult Stage

During their life cycle, root aphids can develop wings, which is why some people mistake them for fungus gnats. However, there are slight differences, like winged root aphids are slimmer than fungus gnats, who are weaker fliers.

Their ability to infest indoor growing facilities is relatively unknown. But there are theories that include females entering through vents or open doors. Infestations by winged adults can cause wilting, stunted growth, and sometimes death.

Root Aphid Prevention

Insecticides don’t really work on root aphids because they usually occur on the outside or bottom of the root ball, where it is hard to penetrate, so if using insecticide, make sure the plant is completely drenched. In addition, their waxy substance provides protection against insecticides.

The best prevention method is to pull plants from their pots and examine the roots for any waxy secretions. If any are found, the best thing to do is to discard the plant entirely.

While they might not be common in greenhouse crops, if any of these plants start to exhibit nutrient deficiencies, it’s best to check them for root aphids.

Related Insects…

• Yellow Aphids
• Green Aphids
• Biscuit Beetle

1. Planet Natural, Available here: https://www.planetnatural.com/pest-problem-solver/houseplant-pests/root-aphid-control/
2. Michigan State University, Available here: https://www.canr.msu.edu/news/root_aphids_the_underground_pest_on_succulent_plants
3. Gardening, Available here: https://gardening.which.co.uk/hc/en-gb/articles/115001015329-Root-aphids
4. ProMix, Available here: https://www.pthorticulture.com/en/training-center/critters-down-under-root-aphids/