Pests go hand in hand with any agricultural venture and as the cannabis industry grows, unexpected agricultural pests are popping up. Battles with thrips, spider mites, even the cannabis aphis are all too well-know in the industry. Recently, a pest known to infest outdoor grass crops has been found on indoor Cannabis sativa crops, the Rhopalosiphum rufiabdominale, or rice root aphid. This pest can cause harmful crop damage from growth stagnation to flower discoloration through a few methods. One way is the rice root aphids will literally suck the life out of the plant, the sap, and, therefore, they are known as “sap suckers”.  Another way these aphids harm crops is through root infestation, stopping the root from absorbing vital nutrients needed by the plant.
While known to infest primarily the roots of outdoor grass crops, the rice root aphid has been found primarily in indoor grows in at least seven states in the US, leading researchers to believe it is prolific in all areas.  While no infestations have been reported in outdoor cannabis crops, the pest has been in North America for at least 100 years and soil testing in all states shows it is possible to have outdoor infestations.
Rice root aphids can infest any part of a plant, from soil to leaves.  Indoor grow temperatures of 25⁰C (77⁰F) and moist soils are the perfect medium for this little bug to proliferate. Combine this with improperly quarantining a new cutting or import, or bad hygiene practices from transplanting, and you may find yourself with an infestation.
While the commercial C. sativa growing industry is still in its infancy, there are no federally approved chemical treatments for infestations; each state has their own list of approved treatments for cannabis. The best practice is to maintain a pest-free environment by isolating transplants and cleaning and sterilizing surfaces and containers . Other options for aphid control include companion planting either as a repellant or a trap plant.  Repellant plants can disrupt insect behaviors through the release of volatile molecules like terpenes. Trap plants lure the pests to them and away from the main crop. Bear in mind companion planting methods were tested for outdoor crops, not indoor operations.
References Ben-Issa R, Gomez L, Gautier H. Companion plants for aphid pest management. Insects. 2017;8(4):112. [journal impact factor = ; times cited = ]  Cranshaw W, & Wainwright-Evans S. Cannabis sativa as a host of rice root aphid (Hemiptera: Aphididae) in North America. Journal of Integrated Pest Management. 2020;11(1):15. [journal impact factor = 2.937; times cited = 1]