Hover Fly Larvae: All You Need to Know for a Healthy Garden

Hover fly larvae are fascinating creatures that play a crucial role in keeping gardens healthy. These tiny larvae, often overlooked by many, are voracious predators of common garden pests like aphids, scale insects, and thrips. By having hover fly larvae in your garden, you can effectively reduce the use of chemical pesticides and protect your plants from harmful insects.

Adult hover flies, belonging to the family Syrphidae, are often mistaken for bees or wasps due to their similar color patterns. These flies can be found hovering around flowers, feeding on nectar and pollen. Interestingly, their bee-like appearance is believed to deter their own predators by mimicking the stinging insects. The larvae, on the other hand, have a completely different appearance and diet preferences.

In this article, we will dive into the world of hover fly larvae, discussing their unique characteristics, life cycle, and the benefits they bring to garden ecosystems. By understanding these small but mighty predators, you can optimize your gardening practices and contribute to a more sustainable and ecological environment.

Hover Fly Larvae Basics

Life Cycle

  • Eggs: Hover fly females lay eggs on plants infested with aphids or other soft-bodied prey.
  • Larvae: Maggots feed voraciously on prey, completing 3 growth stages in about a week.
  • Pupae: Larvae pupate, forming protective cases, and emerge as adults in 7-10 days.

Appearance and Identification

  • Larvae: Pale green, cream or brown in color; elongated, slug-like bodies; tapering at both ends.
  • Adults: Resemble bees or wasps; black with bands or stripes of orange, yellow, or white; large eyes and distinct antennae.

Distribution

Hover flies, also known as syrphid flies or flower flies, are common and important natural enemies of aphids, scale insects, and thrips. They can be found in a variety of habitats, including gardens, orchards, and agricultural fields.

For example, the Scaeva pyrastri species is common in the Pacific Northwest.

Characteristic Hover Fly Larvae Aphids
Body Shape Elongated, slug-like Small, pear-shaped
Color Green, cream, or brown Green or black
Movement Slow, crawling, or wriggling Slow, walking

Pros of hover fly larvae as natural enemies:

  • Effective predators of various pests
  • Larvae consume a significant number of prey
  • Reduce the need for chemical pesticides

Cons of hover fly larvae as natural enemies:

  • May not completely eliminate pests
  • Require a suitable habitat to thrive
  • Not effective against large, fast-moving pests

Benefits in the Garden

Predatory Abilities

Hover fly larvae are excellent predators in the garden. They are known for their ability to control aphid populations. A few key features of their predatory abilities include:

  • High consumption rate: Larvae can consume hundreds of aphids during their development.
  • Wide prey range: They also feed on other pests like caterpillars, thrips, and scale insects.

Pollination Contributions

In addition to their predatory skills, hover flies play a crucial role as pollinators. Adult flies help with flower pollination by:

  • Visiting flowers: They visit flowers for nectar and pollen, which aids in pollination.
  • Attracting other pollinators: Their presence can attract other beneficial insects and pollinators to the garden.

Some examples of flowers that gardeners can plant to attract hover flies include wild carrot (Queen Anne’s lace), wild mustard, sweet alyssum, coriander, and dill. These small-flowered herbs provide both pollen and nectar sources for the adult hover flies. They are also drawn to weedy borders or mixed garden plantings infested with aphids, which provide food for their larvae (source).

Hover Flies Pollinating Bees
Pollinate on nectar and pollen visits Specific to pollination
Predatory larvae control pests No significant pest control

In conclusion, hover fly larvae offer numerous benefits to gardeners. Their abilities to control aphid and other pest populations, along with their role as pollinators, make them valuable assets to any garden.

Attracting Hover Fly Larvae

Plant Selection

Attracting hover fly larvae to your garden starts with the right plant selection. Some plants known to draw hover flies include:

  • Alyssum: Sweet alyssum (Lobularia maritima) has a long bloom period and has been found to be effective in attracting and keeping syrphid flies in an area.
  • Aster: These perennial flowers are known for their ability to attract hover flies.
  • Daisies: Daisies are a great option, as they provide nectar and pollen for adult hover flies.
  • Marigolds: These annual flowers are also effective in drawing hover flies to your garden.
  • Herbs: Some herbs, such as dill, fennel, and parsley, attract hover flies as well.
  • Vegetables: Certain vegetables, like lettuce and spinach, can also help attract hover flies.
  • Weeds: Surprisingly, some weeds like yarrow and Queen Anne’s lace serve as food sources for hover flies.

Creating an Ideal Habitat

Providing a suitable habitat for hover flies is essential for them to thrive and lay eggs. Here are a few tips to create a welcoming space for these beneficial insects:

  • Fruits: Plant fruit trees and berry bushes, which provide an additional food source for hover flies.
  • Hedges: Plant hedges to offer shelter and breeding sites for hover flies.
  • Bird protection: Place birdhouses or bird feeders around your garden to deter birds from eating hover fly larvae.
  • Garden pests: Encourage hover flies by avoiding broad-spectrum pesticides, which kill beneficial insects as well.
  • Flowers: Choose flowers with open blooms or flat surfaces, making it easier for hover flies to feed on pollen and nectar.
  • Leaves: Incorporate plants with various leaf shapes and textures, giving hover flies and their larvae ample places to rest and hunt for prey.
  • Soil: Maintain healthy, well-draining soil to support a biodiverse ecosystem in your garden.

By considering these plant selections and creating an ideal habitat, you can increase the presence of hover fly larvae in your garden, promoting natural pest control and a healthier ecosystem.

Natural Enemies and Pests

Predators

Hover fly larvae, also called syrphid flies, are natural enemies to various pests. They are beneficial for controlling aphids and other small, slow-moving insects. Some common predators of hover fly larvae include:

  • Birds
  • Insects (e.g., certain species of beetles and ants)

Pest Management Techniques

There are several pest management techniques that can be employed to protect hover fly larvae and encourage their role in biological control. These methods include:

  • Minimizing the use of insecticides, as they can harm beneficial insects such as hover fly larvae.
  • Using insecticidal soap, which is less harmful to hover fly larvae and other natural enemies.
  • Welcoming other natural enemies (e.g., ladybugs and parasitic wasps) to enhance pest control.
Technique Pros Cons
Insecticides Can quickly control pest populations Harmful to hover fly larvae and other natural enemies; can lead to pest resistance
Insecticidal Soap Less harmful to natural enemies May require repeated applications for effective control
Encouraging Natural Enemies Supports balanced ecosystem, natural pest control Takes time to establish; requires careful management of the environment

In summary, hover fly larvae play a crucial role in controlling pests within their ecosystem. Taking care to protect them from predators and harmful pest control methods can greatly enhance their effectiveness as a natural enemy.

Mimicry and Misconceptions

Resemblance to Bees and Wasps

Hover fly larvae, found in the family Syrphidae, are known for their fascinating ability to mimic bees and wasps. Some common features include:

  • Black, orange, or yellow stripes on the abdomen
  • Hovering behavior similar to bees and wasps
  • Wings that may resemble those of bees and wasps

However, there are some notable differences, such as:

  • Large eyes on hover fly larvae
  • Antennae that differ from those of bees and wasps

Comparison Table

Hover Fly Larvae Bees and Wasps
Stripes on abdomen Stripes on abdomen
Large eyes Smaller eyes
Distinct antennae Similar antennae between bees and wasps

Harmless Nature

Despite the resemblance, hover fly larvae are harmless and provide numerous benefits in controlling pests. Some key points include:

  • Adult hover flies feed on nectar and are not aggressive
  • They do not possess stingers, as bees and wasps do
  • Larvae contribute to controlling aphid populations

So when you spot a hover fly larvae, don’t fear; they’re not out to sting you! Instead, appreciate their role in maintaining a healthy ecosystem.

Notable Hover Fly Species

Scaeva Pyrastri

Scaeva pyrastri is a common species of hover fly found in Pacific Northwest orchards. These hover flies are also known as:

  • Flower flies
  • Hover flies

Their larvae are predators feeding on:

  • Aphids
  • Scale insects
  • Thrips

Adult Scaeva pyrastri are harmless and feed on nectar and pollen.

Drone Flies

Drone flies are another prominent species of hover flies native to eastern North America. They have yellow and black markings that resemble bees or wasps, which helps protect them from predators.

Their larvae, called “rat-tailed maggots,” consume decaying organic matter in stagnant water. These larvae are beneficial, as they help break down and recycle nutrients.

Comparison Table: Scaeva Pyrastri vs. Drone Flies

Feature Scaeva Pyrastri Drone Flies
Region Pacific Northwest Eastern North America
Larval Diet Aphids, Scale, and Thrips Decaying Organic Matter
Adult Diet Nectar and Pollen Nectar and Pollen
Markings Variable Yellow and Black
Role in Ecosystem Predator of Pest Insects Decomposer and Pollinator

In conclusion, both Scaeva pyrastri and drone flies are essential hover fly species that contribute to a healthy ecosystem. Each species has its specific role, with Scaeva pyrastri focusing on pest control, while drone flies focus on decomposition and pollination.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Possibly Flower Fly Larva found in Organic Salad

 

Subject: Green Slimy Bug in Salad
Location: Portland, OR
August 12, 2017 9:59 am
Howdy,
Found this in my salad after eating at a restaurant. It moved like a leach out of water. Able to elongate its body unlike any maggot I have seen before. No ribbed texture like a maggot. Greenish hue slimy, semi transparent able to see some innards. No obvious mouth parts.
This was in Portland, OR on August 7th. Salad was local organic greens. Wandering what it is for health reasons.
Signature: Harlan Whitman

Possibly Flower Fly Larva

Dear Harlan,
What we sacrifice in not getting pesticides in our food is the occasional appearance of an insect in organic produce.  This looks to us like the larva of a Flower Fly in the family Syrphidae, like the one in this BugGuide image.  Syrphid Fly larvae are beneficial predators that eat large quantities of Aphids, and it makes sense that they might be found in organic greens.

Letter 2 – Bot Fly

 

wooly bear hover fly (eristalis flavipes)?
August 20, 2009
Found at 8700′ elevation on the summit of Robinson Peak in Washington’s Pasayten Wilderness
Tvashtar
8700′ Pasayten Wilderness WA

Woolly Bear Hover Fly
Bot Fly

Dear Tvashtar,
We looked on BugGuide, and we believe your identification of a Woolly Bear Hover Fly, Eristalis flavipes, is correct.  The species mimics Bumble Bees in appearance and behavior.

Correction by Eric Eaton
August 29, 2009
Daniel:
… Thanks for the prompt.  I do have a couple other corrections: …
The “woolly bear hover fly” is actually something much more uncommon:  one of the bot flies that afflicts horses or deer or sheep.  I’ll try to get my friend Jeff Boettner to investigate, as he knows that family very well.  Meanwhile, if the person wants to submit the image to Bugguide, that would be great.  There are precious few images anywhere of these insects. …
Eric

Letter 3 – Flower Fly Larva we believe

 

Subject:  Please help 🙂
Geographic location of the bug:  Northeast Pennsylvania
Date: 10/22/2017
Time: 01:23 AM EDT
My three year old is very well known for his ability to spot the most camouflaged objects, insects, anything. He is the best shed  hunter I know. He found an assassin Bug today that I couldn’t even see while he was pointing at it. But he also found this other… Thing. We were deep in the woods, near a swamp as well as a creek. Pine needles for ground cover mostly, but tons of birch, maple, katalpa, just a huge variety of trees. Also, a huge cliff/rock wall. We like to go here because you can find basically anything in this habitat. But we have such trouble identifying them for that same reason. I imagine it’s a simple ID, but I just can’t find this one. Any help would be appreciated!
How you want your letter signed:  Devon Markarian

Flower Fly larva we believe

Dear Devon,
This is an immature insect and immature phases can be difficult to identify.  We believe this is a Flower Fly larva in the family Syrphidae.  You did not provide a size, and most Flower Fly larvae are under a half an inch in length.  If this was much larger than that, please let us know.  There are Flower Fly larvae pictured on Diptera Info and on the Oregon State University site.

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

3 thoughts on “Hover Fly Larvae: All You Need to Know for a Healthy Garden”

  1. Good eye Eric, I believe you might be right that this is one of five species in the genus Cephenemyia. Neat that you saw it on a mountain top as others in the genus use hilltops to find mates. So this may be a potential lek site. If you go back up keep your eyes out for more. The males play king of the hill and females will mate with the male holding the top when she arrives. I am not as familar with this group but maybe someone out there can confirm the ID.

    Reply
  2. I have a whole nest of these in a large Box Elder in the back of our Admin building. Do they nest in cavities in the trees?

    Reply

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