Hoverflies - Neighborhood Naturalist

Nature you can find in town and the nearby countryside
Corvallis, Oregon
Spring 2012
Hoverflies
article and photography by Lisa Millbank
S
eemingly dangling from an invisible thread, a hoverfly
is a motionless speck illuminated by a spring sunbeam.
Suddenly it dashes away with amazing agility, only to
return seconds later to the same place.
Hoverflies, also known as flower flies or syrphids, can
be very beautiful when seen up close. Some sport metallic
highlights of gold or bronze, sometimes with shining fringes
of bristles. It’s common for hoverflies to mimic bees and
wasps with bold bands of color. Though they can’t bite or
sting, their dangerous appearance helps them buzz around A female Eupeodes americanus on Common Centaury blossoms
the flowers undisturbed. It may take a close look to tell a
hoverfly from a stinging insect. However, crab spiders are (which all flies possess), hoverflies also have a specially
principal predators of hoverflies, and are undeterred by the modified lobe near the base of each wing that flips upward
deceptive coloration, since they also catch bees and wasps. in flight. With each wingbeat, a hoverfly’s entire wing
deforms and twists dramatically. Scientists are investigating
Like all true flies, hoverflies have only two functional the way in which hoverflies’ twisting wings recapture some
wings, unlike the four-winged bees and wasps they may of the energy of the wingbeat by using the vortices that
closely resemble. The rear pair of wings are reduced to tiny, spin off their wings to generate additional lift. Thanks to
knobbed stalks called halteres, which act as a gyroscopic a type of muscle tissue unique to insects, hoverflies can
stabilization system during flight. In addition to the halteres beat their wings up to 300 times per second. Many flies,
such as mosquitoes and even house flies, are accomplished
and efficient fliers, but few can compare to the aerobatic
supremacy of hoverflies.
This male Hadromyia pulchra is feeding on pollen
As you might expect, vision plays a major role in highspeed, precision aerial maneuvers. Hoverflies have superb
full-color vision that may extend into the ultraviolet range
in some species. All hoverflies have two large compound
eyes and three simple eyes on the forehead, but male
hoverflies’ eyes are so large that they meet at the top of the
head. There is a distinct gap between females’ eyes. Since
male hoverflies spend a good part of each day aggressively
chasing other males and pursuing females in attempts to
mate, they need even bigger eyes than females do.
Neighborhood Naturalist, Spring 2012 v10 #1 • page 1
illustrations by Lisa Millbank
A typical garden hoverfly larva is draining the
body of an aphid it has captured. The larva
has no eyes and also doesn’t have any
true legs, but it does have small
leg-like protuberances that
help it get around.
The puparium of a
hoverfly is often hidden
among leaf litter.
During the warm days
of summer, it may take
less than a week to hatch
into an adult fly, but it may also spend the entire winter in
this state.
be attracted to them. Hoverflies prefer wide, flat clusters of
small, shallow flowers. They like fragrant flowers, usually
white to yellow in color, although they’ll eagerly visit
flowers of any color.
Male hoverflies are the ones you might see hovering in
a sunbeam while walking down a wooded path. A male
establishes a territory that females are likely to visit. In many
species, the territory is located either near flowers where
females will come to feed, or near a good site for egg-laying.
The male will pursue just about any moving object he sees.
He chases away other insects, especially other males of his
own kind. But, he also dashes out after females, hoping to
mate (which hoverflies often do in flight). After darting
away to chase an intruder, a male often returns to hover
again at exactly the same spot.
After mating, the female will use chemical and visual
cues to search for a favorable spot to lay her eggs. If her
young eat aphids, she’ll attempt to detect an aphid colony
and lay eggs nearby. Hoverfly eggs are often very elongated
with textured surfaces. Some look almost identical to plant
thorns, camouflaging them from birds and other predators
of insect eggs.
Like houseflies, adult hoverflies have pad-like mouthparts
that they use to suck up liquids. Hoverflies drink nectar
from flowers, but for many species, their primary source
of nutrients comes from pollen. Though it’s not wellunderstood how they do it, hoverflies use their mouthparts
to strip the pollen from flower anthers. Whether sipping
In a sunny garden, the eggs hatch in just a few days. A
nectar or eating pollen, they become liberally dusted with caterpillar-like little green monster emerges from each egg
pollen and inadvertently carry it to the next flower they and begins gorging itself. Eyeless and legless, the voracious
visit, making them excellent pollinators.
larva creeps along, detecting the aphids with chemical
receptors. It grabs an aphid with its hook-like mouthparts,
In fact, many flowers have evolved features that are rips it open, and sucks out its body fluids. All that’s left
particularly attractive to flies, though other insects may also is an empty husk, and the larva starts devouring the next
one. It may take over a thousand aphids to satisfy the larva’s
appetite enough for it to pupate.
Ne i g h b o r h o o d Na t u r a l i s t
promotes interest about nature
in mid-Willamette Valley
backyards, neighborhoods, and
countryside.
Hoverflies are diverse, and some of their larvae are
much more bizarre than the little green aphid-eater. The
Drone Fly has aquatic larvae equipped with their own
snorkel-like breathing tubes. The larva of this introduced
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©2012 Don Boucher and Lisa Millbank.
This male of the Platycheirus genus is hovering in his territory
Neighborhood Naturalist, Spring 2012 v10 #1 • page 2
European hoverfly lives in sewage or other water that
is rich in decaying organic matter, and it can extend its
breathing tube to the water’s surface. Though it’s a harmless
little creature, it looks rather grotesque, and is called a
rat-tailed maggot. One summer, after leaving a container
of beer in our garden as slug bait, we managed to catch a
few inebriated gastropods. The bubbling broth of warm,
fermenting dead slugs and beer was soon full of healthy,
wriggling rat-tailed maggots.
Most of the larvae of our native forest hoverflies live in
decaying wood and share their habitat with many kinds
of beetle larvae, taking part in the cycle of decomposition.
These strange-looking little creatures are often very flat and
disc-shaped, with a tough outer covering. A few types of
hoverflies have larvae that eat living plant material, but the
vast majority are insect predators or scavengers of decaying
material.
A female Scaeva pyrastri extends her pad-like mouthparts
When the larval stage is finished, the larva becomes a
pupa, the stage during which it metamorphoses into an
adult fly. Hoverfly larvae pupate within their exoskeleton,
and this type of pupa is called a puparium. Our typical
garden hoverflies pupate in leaf litter, and the last generation
of the year’s flies overwinter as puparia.
A garden with a mix of flowers and vegetables can attract
a robust hoverfly population. Flowers like yarrow, mints,
asters and fennel suit them very well. Try placing some leaf
mulch around the bases of plants to serve as a good place
for pupation, and leave it undisturbed for overwintering
puparia if you can. Like most beneficial insects, hoverflies
are sensitive to insecticides.
This male of the Melanostoma genus is active very early in the
season, and is feeding on a Spring Beauty flower.
As soon as the weather warms up, adult hoverflies will
be visiting flowers alongside butterflies, bees, beetles and
ants. Hoverflies will be out and about until the onset of
cold weather in fall. ó
Hoverfly Look-alikes
This fuzzy fly is not a hoverfly; it’s a bee fly (Bombylius sp.).
While it’s also excellent at hovering, its long proboscis provides
an easy way to distinguish it from hoverflies. With its proboscis,
it can reach nectar sources that are unavailable to hoverflies,
such as in these Bigleaf Maple blossoms.
Hoverflies can strongly resemble bees and wasps. Bees (like this
Honey Bee) and wasps have smaller eyes and longer antennae
than hoverflies do. They also have four wings, while flies have
only two, but it’s not always easy to count them!
Neighborhood Naturalist, Spring 2012 v10 #1 • page 3
Monkeyflowers
Common
Monkeyflower
by Don Boucher, photography by Lisa Millbank
W
e were looking for rare and unusual plants
in a Willamette Valley lowland forest of ash,
maple and oaks. After navigating the difficult,
tangled undergrowth of dewberry, we came to a wetland
at the upper reaches of a beaver pond. The boundary of
the water was obscured by vegetation and mud. A patch
of delicate green, low-growing plants covered the footswallowing muck. In the few sunbeams that reached the
forest floor were glowing yellow blossoms with an active
community of bees and flies. Monkeyflowers! A familiar
sight, but not exactly like we’re used to seeing. It was Musk
Monkeyflower—not a rare plant, but something we’ve
never seen so close to home. The plants were covered with
fine, moist hairs that were a little bit slimy.
Finally, Tricolored Monkeyflower is a rare species that’s
confined to shallow, seasonal wetlands at low elevations.
Most places that the plant once grew are now cities and
farmland. The plant is just a few inches high, and has a tiny
pink blossom with burgundy spots and a yellow throat. It
may be accompanied by plants like Elegant Downingia,
popcornflowers, Coyote Thistle and bunchgrasses. One
reason it’s rare is because its life cycle requires a particular
kind of seasonal disturbance. In fall and winter, when
the plant has died back, the seeds benefit from moderate
soil disturbance. Usually disturbance comes naturally in
the form of winter flooding. Where some populations
are managed by conservation organizations, measures are
taken to mildly disturb the top inch or two of soil with
equipment to mimic this disturbance. Here’s the catch.
No bushwhacking through the forest is required to From April through July, the delicate plants must go
find Common Monkeyflower. It’s a cosmopolitan plant in totally undisturbed and without competition from weeds.
temperate regions of the Northern Hemisphere. I know of a Tricolored Monkeyflower has a short life cycle and brief
vibrant patch that grows in a flooded ditch along Highway blooming period in June. It’s easy to miss them while they’re
99W, north of Corvallis. You can find this plant in sunny blooming, and the plants are tiny and easy to overlook. It
wet areas from the mountains to the coast. I’ve also found could be that some populations are going unnoticed. Even
them growing at the bottom of rocky seeps or at the edges so, they’re still rare. A population grows at Marys River
of a slow-moving river channels. It has yellow blossoms, Natural Area in Corvallis.
similar to Musk Monkeyflower, but they’re usually larger
and have a variable amount of red spotting. Common
Monkeyflower grows in a bewildering range of sizes, and
the flowers can differ radically from place to place. Some
of these variations may someday be recognized as separate
species, as botanists investigate them further.
While hiking in the Coast Range or Cascade foothills I’ve
found Woods Monkeyflower. In Douglas-Fir and Bigleaf
Maple forests, you might see the yellow, wide-throated
blossoms along creeks or wherever groundwater seeps to
the surface. Another species you might find in the foothills
and mountains is Chickweed Monkeyflower. Locally, it’s
very uncommon and prefers to grow in a layer of moss in
misty areas (near streams and waterfalls).
Tricolored Monkeyflower (Mimulus tricolor). It’s a very tiny plant
and the Willamette Valley’s only pink monkeyflower.
Neighborhood Naturalist, Spring 2012 v10 #1 • page 4
Monkeyflowers have tiny seeds that drop out of small
capsules. Seeds are commonly carried away by water or may
also be dispersed by wind. In some species, like Common
Monkeyflower, seeds may be spread by the scat of deer and
other animals who happen to eat the seed capsules when
they browse on the plants. All of our monkeyflowers are
native.
Monkeyflowers are named for their resemblance to a
monkey’s face. I think it requires some imagination to see
it. Maybe the top petals are the brow ridge, the side petals
the ears and the bottom petal the chin?
Many species, including Common Monkeyflower,
are bred for extra-colorful and fancy flowers and sold to Woods Monkeyflower (Mimulus dentatus). The blossom has a
gardeners. They can be a bit tricky to grow since they broad throat and the leaves have toothed edges.
require specific moist conditions. This makes them better
suited for gardens with ponds or water features. ó
Musk Monkeyflower (Mimulus moschatus). The hairy, slimy
leaves are unique.
Upper Lip
Beard
Throat
Calyx Corolla
Lower Lip
Monkeyflower blossoms are bilaterally symmetric.
That is, the left and right halves are the same, but
the top and bottom halves are different, like flowers
of orchids, peas and mints. The five petals are fused
into a tubular corolla, with two partially-fused petals
on top and three partially-fused petals on bottom.
The top petals are referred to collectively as the upper
lip, and the bottom petals are the lower lip. Inside
the tube, just before the petals separate, is the throat.
In many species, the bottom part of the throat has a
beard, which are hairs or bristles. Sheathing the base of
the corolla is a five-pointed green calyx of fused sepals.
Neighborhood Naturalist, Spring 2012 v10 #1 • page 5
illustration by Don Boucher
All three of these photos (above,
right and below) are forms
of Common Monkeyflower
(Mimulus guttatus). This
variability is due to both growing
conditions and genetics.
Honeysuckles
Hairy Honeysuckle
by Don Boucher, photography by Lisa Millbank
H
ave you ever noticed a Rufous Hummingbird
who “owns” a forest clearing? When he’s not
chasing away rivals, or just looking important
on a prominent perch, he’s busy visiting the brush at the
clearing’s edge. On closer inspection, you might have
noticed he’s been visiting a few dangling clusters of orange
blossoms here and there. Yep, he owns those too! The
blossoms are attached to vines trailing through and around
some of the young trees. The tubular flowers hold a lot
of nectar—a resource worthy of the best hummingbird
defense measures.
forests. Unlike Orange Honeysuckle, the entire plant is
hairy. Otherwise, the leaves are similar, but the terminal,
joined pair of leaves are smaller. It has cluster of long,
slender pink blossoms which develop into red fruits.
That’s Orange Honeysuckle (Lonicera ciliosa), and
it’s widespread in Western Oregon from low- to midelevations. It’s more common in the mountains, but it’s also
found in the valley at the edges of shady forests, usually
with conifers. It’s quite distinctive with its opposite pairs
of oval leaves which partially clasp the thin, trailing stems.
The leaves have fringes of short hairs on the edges. But
most notable is the terminal pair of leaves, which are joined
into one large oval. Growing from the center of this oval
is a stem bearing one to three flower clusters. Later in the
season, they produce clusters of red fruits.
Honeysuckles are related to snowberries. Some
Honeysuckle species native to Asia are commonly used
in our area for landscaping and have a reputation for
their potent, sweet fragrance. Our native species have a
nice fragrance too, but not quite as intense as the hybrids
bred for the purpose. The native honeysuckles are worthy
landscaping alternatives to the Asian species. Natives are
already to adapted to thrive in our climate, and there’s an
eager army of native pollinators who are up to the task.
Hairy Honeysuckle (Lonicera hispidula) is a similar vine,
which grows in lowland forests like oak woodlands. It isn’t
widely common in our area, preferring drier, more open
Our other honeysuckle looks bit different. It’s called
Black Twinberry (Lonicera involucrata). It’s a shrub of moist
areas and uncommon here. The leaf pairs don’t join together
or clasp the stems. The yellow blossoms are a pair of stout
tubes that emerge from a base of sturdy bracts. The resulting
fruits are black and glossy, with deep red bracts at their base.
Whether in the wild or in your yard, enjoy the fragrant
flowers of our native honeysuckles, and the inevitable visits
from hummingbirds and other pollinators. Leave the pretty
fruits to the birds, as they are toxic (but not very dangerous)
and terribly bitter to humans. ó
Neighborhood Naturalist, Spring 2012 v10 #1 • page 6
Orange
Honeysuckle
Black
Twinberry
Hairy Honeysuckle
Neighborhood Naturalist, Spring 2012 v10 #1 • page 7
fruit illustrations by Don Boucher
Our Native Honeysuckles
Natural Areas Celebration Week
May 5-13, 2012
Please join us for these Neighborhood Naturalist-sponsored field trips
Events are free, no registration required
Sunday, May 6th
Birdsong Walk – 8-11am
Meet us at Willamette Park, Crystal Lake Sports
Fields /Boat Ramp Parking Area
Talking Water Gardens Walk – 5-8pm
Meet us at Talking Water Gardens/Simpson Park
parking area (778 Waverly Dr. NE), Albany
Wednesday, May 9th
Saturday, May 12th
Bat Night – 8:45-10pm
Meet us at Bruce Starker Arts Park parking lot (near
duck pond and amphitheater)
For more information on these events,
visit the events page on our website or
contact us at 541-753-7689,
[email protected]
Jackson-Frazier Wetland Tour – 9am-Noon
Meet us at Jackson-Frazier boardwalk at
the end of Lancaster St.
There are also more than a dozen other events sponsored by
other organizations. Visit the Corvallis Sustainability Coalition’s
website for more information:
sustainablecorvallis.org/action-teams/natural-areas/
In this issue:
Hoverflies
Neighborhood Naturalist
5008 Technology Loop #9
Corvallis, OR 97333
Monkeyflowers
Honeysuckles
Events
Naturalist Adventures
Third Sunday of the Month, 9am-Noon
April 15 • May 20 • June 17 • July 15 • August 19
All trips meet at Avery Park Rose Garden: 1210 SW Avery Dr., Corvallis
Come learn or share your knowledge about nature in the Willamette Valley. We look at birds,
flowers, animal tracks and all kinds of other things. Our nature walks are slow-paced and casually
structured. Bring along a hat, rain gear and shoes that can get muddy. Please, no dogs. Activities
are geared toward adults but children may enjoy them too.
Rain or cold will not prevent us from going out and enjoying nature. Remember to dress for the rainy
and/or cold weather.
For other events or more information:
www.neighborhood-naturalist.com
Don Boucher, 541-753-7689, [email protected]
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