Aphids and aphid mummies on the underside of a nasturtium leaf (smoky gray aphids, tan puffy aphid mummies)
For some gardeners, the mere sight of aphids on their beloved plants is a call to action. They grab the closest bottle of poison and squirt the aphids into oblivion. What many gardeners don’t realize is that aphids are the food of choice for an assortment of beneficial insects. These good bugs are likely hard at work among every aphid infestation, munching, laying eggs for the next generation inside their unsuspecting prey, or sucking the aphid carcasses dry. One squirt from the bottle of insecticide will kill some (not all) of the aphids, and most of the beneficial insects.
If only we could easily tell at first glance that beneficial insects are on the scene! They don’t wear white hats or wave flags to alert gardeners to their presence. Instead, beneficial insects creep, crawl and squirm across our plants, often appearing as if they could be the cause of damage, not the cure.
Take hover fly larvae, for example. As adults, these bee-mimics visit flowers, feeding on nectar and pollen. When the female finds an aphid population, she lays her eggs on the infested plant. Like all flies, the hover fly juvenile stage is a maggot, in this case a small maggot that feeds on aphids. The legless, semi-transparent hover fly larva hardly looks the part of a beneficial insect, but each individual can eat dozens of aphids every day.
Lady beetle eggs (yellow) on a purple leaf plum leaf.
Another aphid-killer that feeds in the larval stage is the lacewing. As adults, these delicate insects with netted wings feed mainly on pollen and nectar. Lacewing larvae, sometimes called “aphid-lions”, are efficient predators, stalking down aphids and piercing them with their hooked jaws. After removing the contents from the aphid’s body, the lacewing larva casts aside the empty aphid carcass, and heads off in search of another victim.
Ladybird beetles are also voracious predators of aphids, feeding in both the adult and the larval stage. Like hover flies, ladybird beetles (also known as ladybugs) will lay their yellow, spindle-shaped eggs on plants that have active aphid colonies. The beetle larvae look nothing like the adult ladybug. They are spiny and elongated, sometimes compared to baby alligators. These active hunters crawl over leaves and across stems to find their next meal.
Parasitic wasps are another group of aphid-eating insects unlikely to be noticed by the uninitiated. The tiny female wasp stings individual aphids, laying an egg inside the aphid’s body. The egg hatches into a wasp larva, which eats the aphid from the inside, killing its victim and causing its body to become papery and swollen. These so-called “aphid mummies” can be seen in aphid colonies; some mummies will have a round hole where the adult wasp emerged to begin the cycle again.
Lady beetle larva
When the gardener rushes for the bottle of insecticide, the predators will likely be killed, but surely not every aphid will die. Since aphids can be born pregnant with their granddaughters, their populations can skyrocket in the absence of beneficial insects.
These aphid predators will in time bring balance to the garden, keeping aphid populations down to a dull roar. If the predators are allowed to complete their lives in the garden – meaning the gardener has provided a habitat with plenty of flowers and a few aphids to feed upon – they are likely to stick around, ready to feed on any future aphid outbreaks.
So the next time you see aphids, grab a magnifying glass and take a closer look. Chances are, the good guys are already on the scene.
Thank You Denise for your Guest Blog!
Two Barn Farm 
What a great read, lots of useful info thank you Denise and Soulsburyfarm farm, for bring it to us.
Wow! You have your blog out already. Either you’re up with Zoey; or you’re getting ready to take Doug & Liz to the airport! Or both.
Sent from my iPad
Interesting, I think it’s just habit to kill anything that we think doesn’t belong!
I naturally assume those with aphids have tried planting Dill, Fennel, Anise, Mustard, Tansy ?
Apparently Basil & Coriander (Cilantro in the US), also deter Aphids.
That’s pretty close to the list of plants I would suggest to feed adult hover flies, lacewings, and ladybugs.
Great article and very helpful pictures!
Great post and a good reminder to think before you reach for the “X X” 😉
How do I handle aphids on an indoor ornamental plant collection?
Great, informational post! Thank you.
I don’t use chemicals but a hose to hose off the whole crowd when I see aphids on the end of my purple Allamanda which appears to be high on their diet. I let the roving ants sort out the bodies in the grass.
Great info, thanks for sharing!
Great information about aphids and beneficial insects. I’m glad you pointed out how everything is in balance…if you poison one thing, you upset the balance.
When I saw ‘OSU’ after Denise Ellsworth’s name, I was hoping we could claim her here in Oregon, but then I realized it was Ohio State U. You are lucky to have her
Just when I thought that all bugs were bad, but I am just a girl and we hate bugs & crawly things! LOL Great post Dan! (tell Mindy we said Hi)
I wish those predators would come and visit my nasturtiums. They are covered in black flies and I haven’t found anything that wants to eat them so far! We’ve had such peculiar weather so far this summer that I think all the insects are hatching out at the wrong times and it’s all getting a bit jumbled up.
Reblogged this on Adventures and Musings of a Hedgewitch and commented:
Love them! I especially seeing the little alligator like ladybug larve!
Oh my goodness, but this is helpful! I have noticed the wasps, for instance, and couldn’t figure out where they came from or what purpose they could serve! I have a lot to learn, and this was an illuminating start! Thank you! Debra
Very helpful! A great post to encourage thinking in terms of integrated pest management. Thank you!
Wonderful post! Thank you for the information!
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aphids can be born pregnant with their granddaughters- Huh?!! Gross!! 🙂
Reblogged this on gardensunshine and commented:
Don’t be in a hurry to upset the natural balance of bugs in your yard.
GREAT post. Love that aphids are good food for predatory bugs.
Thank you so much for this post! I did not know which plants to grow to encourage aphid eaters, so this is very helpful!
Excellent post. I don’t use insecticides and have minimal trouble with aphids and other pests, and I’m convinced it’s because I attract lots of beneficials. However, I don’t know much about beneficial species, so I enjoyed. this.
This is great information–we’ve used ladybugs as our primary “insecticide” for the past few years and they work great. We bought so many of them last year that they’re back this year in droves. We have a new insect–Robberflies–in our yard this year. I’ve noticed that they eat bees but do you know if they also eat the bugs that eat my garden?
I didn’t even think of BUYING ladybugs!!! I will say those ladybug eggs look an awful lot like Mexican bean beetle eggs. I’ve got to get better at identifying (without bringing my computer or bug book out to the garden) but this is great advice and info–thanks!
They usually sell ladybugs at some of the better garden centers–ours keeps them in the fridge (fully grown) in packs of 2000 or so–the kids love releasing them into the yard!
so cool! I’ll be looking into that, would it be worth it to do it at this point in the year or should we wait until next spring?
I would probably wait until spring. Good luck!
GREAT blog posting!
Very cool!
There definitely is a need for more post like this on beneficial insects and natural garden care. Insecticides are not part of my garden care. I would rather see many different types of insects in the garden than none at all.