When most people see aphids on their plants they immediately seek help on how to eliminate them often grabbing a bottle of soapy water or some other recommended concoction. Me? I get positively giddy with delight.
You see, aphids are on one of the low rungs on the web of life partner’s ladder. They serve as a feast for others, growing a variety of pollinators and ultimately reptiles, amphibians and birds. Where there are aphids, critters on the next link in the food chain are sure to follow.
I’ve written before how aphids are much like butterflies in that they flock to particular host plants. You can often identify the species by using the aphid host database although you might only narrow things down to genus.
This week I got giddy…VERY giddy. I spotted some aphids on the Bidens alba, my all-time favorite Florida native plant. You would be hard-pressed to find any aphid damage on the B. alba…it grows quickly and any chewing or sucking damage is quickly covered by new leaf growth. More importantly, what followed my spotting of the aphids was a parade of critters and the benefits abound.
So, what infantrymen were on my Bidens battlefield?
Hover [syrphid] flies. “A single syrphid larva can consume hundreds of aphids in a month.”
Not to be outdone, the airmen showed up:
Long legged flies. As adults, Longlegged Flies (Dolichopodidae family) are predaceous on small insects such as aphids. And with their metallic colors they’re pretty too!
In my research I learned about a new-to-me aphid web of life partner. The Braconid wasp. While cropping photos I noticed an insect I was not familiar with. Turns out it was an “aphid mummy”. Braconid wasps in the subfamily Aphidiinae are parasitoids and oviposit their eggs in aphids. What I was seeing was an aphid that had been parasitized. Soon a tiny beneficial wasp will emerge.
The waste aphids produce is known as [honeydew]. I found the following of interest:
Adult hover [syrphid] flies require honeydew or nectar and pollen to ensure reproduction, whereas larvae usually require aphid feeding to complete their development (Schneider 1969). However, there are exceptions: in the absence of aphids, larvae of some species can subsist and complete development on diets made up solely of plant materials such as pollen (e.g., Melanostoma and Allograpta obliqua [Schneider 1969] and To x o m e r u s [Mesograpta sp.] [Cole and Schlinger 1969])
So, if you remove aphids from your plants you may defeat attracting future generations of beneficials. Given, I would treat aphids on a houseplant by wiping them off since natural predators won’t have ready access to perform pest control indoors and thus the plant would suffer. On the other hand, its seems that aphids on your outdoor plants can benefit your garden by attracting those wonderful pollinators, predators and parasitoids especially those whose larvae use aphids as hosts.
Don’t spray the aphids and then buy commercial ladybugs in an attempt to keep them in check. Likely, you’ll only to have them fly off. If you already removed the aphids or discouraged them in any way, adult ladybugs will go to lay their eggs where there is an ample supply of the host for their young…like my house. 😉
While other branches of the Bidens had signs of aphids from time to time, the branch in the original photo was scoured clean within a day. Give natural control a chance to develop and hopefully you will see the circle of life perform beautifully at your place too.
Tip: Group different genera of plants native to your area using the “right plant, right place” theory and avoid monocultures. That way your garden will attract a mix of native insects and predators and never look overly chewed since it will have balance just like Mother Nature intended.
ENTFACT-105: Ladybugs by Ric Bessin, Extension Entomologist, University of Kentucky College of Agriculture
Hoffmann, M.P. and Frodsham, A.C. (1993) Natural Enemies of Vegetable Insect Pests. Cooperative Extension, Cornell University, Ithaca, NY. 63 pp. (Anthony Shelton, editor). Accessed August 27, 2017, from http://www.biocontrol.entomology.cornell.edu/