Got Aphids?

Of course you do. We all do. Ugh. It starts slowly enough, you see a few here and there, and seemingly overnight, they’re everywhere, blanketing our favas, kale, broccoli…all our cool season crops and almost anything with young tender growth. How does this happen, what are they doing, and what do we do about it? Here’s what I’ve learned.

Aphids are sucking insects. They use their long slender mouthparts to pierce tender plant tissue and suck out fluids. There are many many species, and they can be green, yellow, brown, red, or black. They reproduce with lightning speed and big infestations can compromise our plants.

Here's 8 fascinating, yet kind of creepy facts about aphids:

  1. They can produce up to 12 offspring per day.
  2. Most aphids reproduce asexually, no males needed.
  3. In this asexual reproduction, females birth live offspring that are clones of themselves.
  4. Offspring are born pregnant, and their offspring are born pregnant, and so on.
  5. When weather is warm, aphids can develop from newborn to reproducing adult in 7-8 days.
  6. When a plant becomes too crowded or its quality deteriorates, they produce winged offspring that can disperse to new plants.
  7. Ants feed on the sweet honeydew that aphids poop out.
  8. Ants farm aphids. They protect them from predators, transport them, and are known to 'milk' the honeydew from them.

The good news 
They don’t do well in heat, so are usually gone from our gardens by June. Well, that’s great, but what about the gazillions of them in the garden now?

Predators to the rescue
Most of us have heard that ladybugs eat aphids, but even a lot of ladybugs can’t keep up, right?  Fortunately, lots of insects like eating aphids:
     • Ladybug larvae and nymphs
     • Soldier Beetles
     • Parasitic mini-wasps - they insert their eggs inside the aphid
       and the larvae eat the aphid.
     • Green lacewings
     • Syrphid flies - they too insert their eggs inside the aphid. 

These beneficial predators can get an aphid problem under control pretty effectively, and they show up naturally. In my garden, I've noticed that the aphids show up first, then ladybugs. The ladybugs don’t keep up with the onslaught, but then the soldier beetles come, and that’s a sign that it’s about to get real. Soon after, predators are everywhere, and frankly, it’s fun to watch. Life abound!

The key to drawing and keeping predators is to include plants in the garden that provide shelter, nectar and pollen for them and plants with lacy foliage are particularly attractive to predators. Here’s just a few examples:
     • Phacelia - Bee's Friend
     • Curly Tansy
     • Golden Marguerite
     • Bronze Fennel
     • Yarrow

What about sprays?
I just don’t. If you spray something that kills aphids, you kill the good bugs too. Wiping out good bugs leaves the aphids to multiply uninterrupted, so you’d actually be selecting for aphids.

Other Controls
     • Hose them off. It works quite well if you're willing to do it periodically.
     • Control ants. These guys are such a pain and control requires patience. Use a 1% boric acid bait in a good refillable bait station and place stations in many places around your property. Those stupid tiny bait stations you get at the hardware store are a joke. Best to get bigger refillable stations you can secure around the yard, hold a lot of bait and don't dry out easily.  See what UC IPM has to say about that here.  

We can’t keep aphids from coming, and we can’t get rid of 100% of them, but our plants can still thrive when we intervene lightly, and encourage nature to balance things out.