Bee Flies – the family Bombyliidae

 

 

Regional gardeners are learning to appreciate native pollinators, in part due to the activities of National Pollinator Week (the 3^rd week in June).  While most people think of bees when they hear the word ‘pollinator’, in fact a wide range of animals function as pollinators.  To learn more about pollinators in general see our June 2013 posting (http://mother-natures-backyard.blogspot.com/2013/06/life-friendly-gardening-planning-for.html).

Among the bee-like insects that serve as pollinators are the Bee Flies.  The Family Bombyliidae is a large family of flies with literally hundreds of genera and thousands of species worldwide. The exact number of species is currently unknown, due to a significant lack of research on this family.  For a good review of the main types of  flies seen in Southern California see: http://waynesword.palomar.edu/redmite6.htm

Like the native bees, Bee Flies range in size from almost microscopic (1 mm/0.05     inches) to large (40 mm/1.5 inches).   The evolutionary relationships between members of this family – and between this and other insect families – are currently poorly understood.   For more on this topic see: http://en.wikipedia.org/wiki/Bombyliidae

Comparison of Bee Fly and Native Bee

Many species superficially resemble bees; hence the common name ‘Bee Flies’.   Their bodies tend to be compact and dense (like a bee) with a rounded head; their coloration may also mimic that of bees.   However, Bee Flies differ from bees in several important ways: 1) a single pair of wings (bees have two pairs) held in a characteristic, swept back (‘bomber’) position when perched (see above) ; 2) no stinger; 3) very large, compound eyes (compare above); 4) segmented antennae; 5) mouths adapted to sucking; 6) long, thin legs (see above).  

Bee Flies usually are black or dark gray in color, sometimes with yellow, gold or white. Their segmented abdomens (the ‘tail end’ part of the insect) may have alternating dark and light segments.   They also tend to be hairy; prominent hairs are often visible on head, thorax (mid-segment) and abdomen (see photo above).

Adult Bee Flies feed on nectar and (sometimes) pollen.  In fact, many have mouth parts adapted for feeding on a particular species/group of plants (an example of specialization). Many have a long proboscis (tube-like, sucking mouth part) for sipping nectar.  Unlike a butterfly proboscis, which is slender and uncoils for feeding, the Bee Fly proboscis is stout and rigid.  You can often observe it in a good photograph of a Bee Fly.

Unlike bees, Bee Flies often don’t actually land when feeding.  They hover above the flower, steadying themselves with their front legs.  In fact, the front legs in some species are notably shorter and more slender than the other legs - an adaptation to hover-feeding.   This hover-feeding behavior may be the first clue that you’re observing a Bee fly, not a bee.

While not as specialized as the bees, Bee Fly species are thought to be important pollinators, particularly in dry climates.  Their frequent visits to flowers and hairy bodies facilitate the movement of pollen from flower to flower.  They likely function as pollinators in local gardens as well as in the wild.

The larvae of Bee Flies are predators or parasites of other insects, often the larvae or juveniles of ground-dwelling bees and wasps, butterflies/moths, grasshoppers,  beetles, Neuroptera (lacewings, antlions)  and other Diptera (flies, gnats, midges).  Many Bee Fly larvae are generalist predators; they feed on several species, depending on availability.  Eggs are often laid in or near insect burrows, providing the larvae with easy access to food..   

While the larval food aspect can be alarming (particularly for those interested in conserving the solitary native bees), Bee Flies may actually play an important role in controlling populations of grasshoppers, beetles and other pest insects.   They are a normal part of the local ecosystem, helping maintain the balance of plants, insects and other creatures.   A functioning, sustainable garden ecosystem should also contain some Bee Flies, at least in dry areas like Southern California.  

A number of Bee Fly species are known from Southern California, particularly in the wilds. The best source of photos that we’ve found is Dr. Peter J. Bryant’s  Natural History of Orange County and Nearby Places : http://nathistoc.bio.uci.edu/diptera/Bombyliidae.htm    Unfortunately, local Bee Flies  are not well-studied; so the number of species and details of their life history are poorly documented.  While this lack of information is lamentable, it also presents a great opportunity for the observant citizen scientist.   In our next posting (July, 2015), we’ll give some hints on photographing and studying pollinators.

 

Bee Fly (Villa lateralis) on Common yarrow (Achillea millefolia)
Mother Nature's Backyard garden, Gardena California

Villa lateralis

The Bee Fly species we see with some regularity in local native plant gardens is Villa lateralis. The genus Villa contains over 250 species, found on all continents except Antarctica.   In the U.S., most Villa species tend to be western. 

Villa flies have rounded heads, clear or smoky wings with a distinctive, simple vein pattern, and a ‘chunky’ body with striped abdomen.    The genus has not been extensively studied, and the last North American taxonomic review is over 100 years old [1].  Hence, it may be difficult to key individuals out to the species level.   In fact, the exact number of Villa species is not currently known.

The local Villa lateralis (also known as Anthrax lateralis var. perimele) is widely distributed from North America to Panama, including Southern California.   The species has variable morphology and can be difficult to classify. Individuals from Eastern North America appear to be distinct from those of the West.

Local individuals we’ve seen have black bodies with prominent gold-yellow hairs on the thorax.  The abdomen has alternating stripes of black, yellow-gold and white (see below).   If you look closely you can see the different colored hairs on the stripes.  The alternating colored stripes are the most distinctive feature seen with the naked eye.

Bee Fly (Villa lateralis) on Common yarrow (Achillea millefolia)
Note wing veins and stout proboscis.

The wings of Villa lateralis have a simple, characteristic vein pattern (see above and   http://www.drawwing.org/insect/villa-lateralis-wing).  The proboscis is stout and not overly long – about as long as the width of the head.  You can see it in the photograph above, as the insect sips nectar from a Yarrow flower.

This species seems to favor plants in the Sunflower family (Asteraceae), at least in local gardens. We’ve observed them most often in June and July in native plant gardens.  We’ve seen them feeding on late-blooming bush sunflowers (Encelia californica), common Yarrow (Achillea millefolium), Goldenrods (Solidago species and Euthamia occidentalis), Telegraph plant (Heterotheca grandiflora) and Goldenbushes (Hazardia species).  The Natural History of Orange County and Nearby Places has several photographs of Villa lateralis on Buckwheat (Eriogonum species) and Alkali heliotrope (Heliotropium curassavicum var. oculatum) flowers; we’ll need to look for them on these garden flowers as well.

 

Bee Fly (Villa lateralis) - Mother Nature's Backyard garden, Gardena California

In a study in Oregon [2], Villa lateralis was found to be a specialist pollinator for several Asteraceae species (Erigeron foliosus; Eriophyllum lanatum; Haplopappus hallii; Solidago Canadensis).   We suspect that it may be functioning as a pollinator in local wildlands and gardens as well.  We hope some enterprising student will study this species in depth sometime soon!

Very little is known about the larval foods of Villa lateralis in Southern California. The larvae of several species of Villa destroy grasshopper eggs; others are parasitic on caterpillars. But almost nothing has been published about this species in Southern California.  If you know someone in search of a research topic, the life history of Villa lateralis is up for grabs!

For pictures and more information on this interesting species we recommend:

http://nathistoc.bio.uci.edu/diptera/Villa3.htm

 http://pick5.pick.uga.edu/mp/20q?search=Villa+lateralis#Hosts

http://pick5.pick.uga.edu/mp/20q?search=Villa+lateralis

 

_________

1.      D.W. Coquillett – Monograph of the species belonging to the genus Anthrax from America North of Mexico.  Transactions of the American Entomological Society and Proceedings of the Entomological Section of the Academy of Natural Sciences Vol. 14 (1887), pp. 159-182.  http://www.jstor.org/stable/25076488

2.       D. Yu - How do the pollinators' flower preferences affect the features of the pollination network? http://eco-informatics.engr.oregonstate.edu/previous/2014/Yu_paper.pdf

 

 

We encourage your comments below.   If you have questions about Bee Flies or other gardening topics you can e-mail us at :  mothernaturesbackyard10@gmail.com

 

 

 

Plant of the Month (March) : California Bush Sunflower – Encelia californica

Early-blooming plants gladden the heart, hinting of approaching spring.  They also provide food for hungry bees and other insects.  One of the most dependable – and cheery – of our early blooming shrubs is the Bush Sunflower.  It is an easy-care mainstay in many local gardens and natural areas.

Also known as California Encelia and Coastal Bush Sunflower, Encelia californica is a member of the Sunflower family (Asteraceae).   It’s a plant of western California from Santa Barbara County to Baja California.   In nature, California Encelia grows mostly along the coast, including the coastal foothills.   It’s an important member of several Southern California plant communities including the Coastal Strand,  Coastal Sage Scrub and Coastal Chaparral communities.  Its inland counterpart, Encelia farinosa, is found in similar plant communities further inland (foothills of the San Gabriel Mountains and desert mountain ranges).

California Encelia is a semi-woody sub-shrub.  The lower parts of its branches are woody while the upper parts are more herbaceous.   It has a mounded shape that’s 2-4 feet tall and 3-6 feet wide.  In many ways, it’s a good example of how local shrubs succeed in our dry mediterranean climate.  In nature – and in the dry garden – Encelia loses all its leaves during the dry summer months.   While this may sound unattractive, a summer-dormant Encelia is not necessarily a detractive element in the garden.  When used as a background plant, the dormant branches serve as a neutral backdrop to greener and more colorful summer plants.

 

California Encelia re-sprouts with the winter rains

With the fall/winter rains, California Encelia greens up rapidly.  New growth sprouts from the woody branches and within a month the plant is fresh and lovely.  The leaves are simple, 3-veined and medium green that becomes darker with age.  The foliage is particularly attractive if the plant has been pruned in the fall.  

Even a child can tell that California Encelia is a sunflower.   It blooms during the rainy season – most often beginning in February and continuing even into May.  The bloom season is dependent on weather conditions, particularly rain and temperature.   The flower head is typical of the composite arrangement that makes the Sunflower Family so popular.   The old name for this family – the Compositae – reflected the composite nature of the flowers.

 

The ‘flower’ of sunflowers is actually a flower head that contains many small flowers.  The ray flowers (many people call these the ‘petals’) are flat and located to the outside of the flowering head.  Not all Sunflower species have prominent ray flowers, but those of Encelia are large and a bright golden yellow.  The central ‘disk’ flowers are smaller and often darker than the ray flowers, although they may be yellow, orange, purple, brown or other colors.  In Encelia, the disk flowers are predominantly dark red-brown.

The entire flowering head is 2-3 inches across and the heads are held above the foliage on slender stems.  A mature Encelia will literally be covered with hundreds of blooms, making it one of our showiest early spring shrubs.   Like the California Poppy, Encelia makes our spring gardens uniquely Southern Californian.

 

Mature Encelia californica in bloom

California Encelia does well in full sun or part shade.  It appreciates afternoon shade if you have a very hot, sunny garden.  It grows in most soil textures and takes soil pH up to 8.0 or so.  It also does fine in salty soils and seaside conditions, making it a useful plant along the immediate coast.   An occasional frost may nip the leaves but rarely kills a plant in our area.  However, California Encelia is a plant of temperate coastal climates; cold winters will surely kill it.

Watering is something of a matter of preference.  Encelias are really tough plants that do fine with little or no supplemental water after the first summer.   We have mature Encelias in the Gardena Willows Wetland Preserve (where Mother Nature’s Backyard is located) that are never watered but look lovely every spring. 

 

California Encelia (background) with annual wildflowers

In the garden setting, some prefer to keep Encelia green through summer with a little irrigation.    The choice is yours.  The drawback to summer water is that you likely will shorten the plant’s life.  If you do choose to water, limit watering to one deep watering a month (let the ground dry out between waterings – Water Zone 1-2 or 2; see     2012 posting on Water Zones) and withhold irrigation after mid-August.  Encelia, like many of our local native plants, needs a rest period during the dry season.

 

Mature Encelia californica pruned in late fall.  Note the seedings
sprouting around the parent plant - plants reseed naturally.

In the wilds, the tender branch tips of California Encelia are nibbled back each summer by deer, rabbits and other browsers.   They can take this abuse and in fact look more youthful because of it.  You can rejuvenate your Encelia by pruning it back quite severely each fall.   This is a scary undertaking the first time you do it – you literally prune the branches down to about 6-8 inches (see photo above).  But if you prune Encelia each year it will reward you with a lovely shape and abundant flowers.  Remember, you’re just doing a job the deer would do in the wild.   You can cut up the trimmings and use them as mulch or compost them.

Encelia is a good choice for the home garden.  In fact, no garden featuring local native plants would be complete without at least one.   It’s fast-growing and makes a good filler around other, slower-growing shrubs.  It does well on slopes, making it useful for hillside gardens.  The flowers make nice cut flowers.  Encelia does smell like a Sunflower;  some consider the smell to be ‘strong’ although we find it simply reminiscent of being out in nature.

 

This California Encelia was pruned 1-2 months prior to this photo

California Encelia is a wonderful habitat plant.  As an early bloomer, it attracts scores of early spring pollinators including European Honey Bees, native bees, fly pollinators, butterflies – even beetles. The foliage of Encelia and Mulefat (Baccharis salicifolia) are larval food plants for the Fatal Metalmark butterfly (Calephelis nemesis).  The seeds are gobbled up by seed eating birds like Goldfinches from late spring through fall.   The shrubs themselves provide important cover for ground-feeding birds, lizards and other animals.

California Encelia was an important medicinal plant for the local Gabrielino/Tongva people.  All parts of the plant were mashed and boiled to form a thick paste (poultice) that was spread on aching joints; the paste was also dissolved in warm water as a soothing bath to decrease the pain of rheumatism.  A paste from above-ground parts was spread on gums and teeth to ease toothache.   A poultice from green leaves was used to treat wounds and the stems were chewed as a breath freshener.   Coastal Encelia’s inland counterpart -  the gray-green Encelia farinosa – was dried and used as a ceremonial incense.

For a gardening information sheet see: http://www.slideshare.net/cvadheim/encelia-californica

For more pictures of this plant see: http://www.slideshare.net/cvadheim/encelia-californica-web-show

 

 

 

We welcome your comments (below).  You can also send your questions to: mothernaturesbackyard10@gmail.com

    

Plant of the Month (September) : Sweetscent (Salt-marsh Fleabane) - Pluchea odorata

Mother Nature’s Backyard features pink and purple flowers. While there are a sprinkling of other flower colors, this theme helps tie together the many plant species featured in our garden. One of our favorite pink-purple species – Sweetscent or Salt-marsh Fleabane – is in peak bloom around our rain garden this month.

Pluchea odorata 

(pronounced PLOO-shuh oh-dor-AY-tuh) is a plant of moist places including brackish marshes, freshwater springs/marshes and other seasonally moist places. It can be found from the west to the east coast of North America and south to the Caribbean Islands and northern South America. Locally, it grew along streams and marshes in western Los Angeles county and on Catalina Island. There likely were patches of it along the Dominguez Slough and Dominguez Creek.

Sweetscent is a member of the Sunflower family (Asteraceae) and its flowers look similar (except in color) to those of Mule Fat (Baccharis salicifolia) another local Sunflower. Pluchea can grow as an annual or perennial, depending on winter temperatures and the amount of summer water. It has rather stout, 2-4 ft upright stems that may become woody at the base but are mostly herbaceous. The leaves are simple, oval to lance-shaped and alternate on the stem. The leaves and stems are dotted with glands that release a mildly camphor-like scent when rubbed or brushed against. To some, the foliage scent is down-right weird. To others, it is a traditional scent associated with our local wetlands. We find it an unusual – but refreshing – addition to our rain garden.

One of the best features of Sweetscent is its colors. If you like pastels – and your tastes run to pink-purple – you should consider growing this plant. The foliage is a pale green pastel – one of the prettiest greens around. Contrast this with the purple flowers and you have an artist’s dream. Monet would have loved the clouds of pink-violet-purple flowers that seem to float like clouds above the pastel foliage.

Like sunflowers in general, Sweetscent has many small flowers that grow in dense clusters (think of the ‘heads’ of sunflowers). As seen above, each flower head includes a number of flat ray flowers surrounding a small number of disc flowers. The heads are grouped in rather loose, flat clusters – located primarily above the foliage. Pluchea blooms from late summer into fall, making it an important color spot in the fall garden. The sweet scent of the flowers – and the abundant nectar – attract a wide range of insects.

The insect visitors are mostly of the smaller variety: the smaller butterflies like Skippers, Blues and Hairstreaks and native bees and small flies. You can easily spend a delightful hour watching the variety of insects attracted to this plant - so be sure to plan seating close by. Below are pictures of just some of the insects we saw on a recent morning. We’ll introduce you the Metallic Green Bee in a posting later this month (September, 2012).

Pluchea will grow in just about any garden soil including those that are alkali and salty. If you have clay soil you’re in luck – Pluchea does very well in local clay soils. Pluchea likes full sun to part-shade. It prefers regular water (Water Zone 2-3 or 3 – see April 26, 2012 posting for more on Water Zone Gardening) although it can take drier conditions once established (occasional water – Water Zone 2). We planted it around our rain garden where it can take advantage of some summer water (we currently water every three days in this part of the garden). This plant can also take the seasonal flooding it will get in the rain garden.

Pluchea spreads via rhizomes. In our experience, the spread is not particularly vigorous – but we manage our garden on the dry side which will decrease the rate of spread. If spread concerns you, Sweetscent does fine in a large container. It will thrive around a lawn, pond or any water feature that provides some summer water. It looks right at home when combined with native warm weather grasses, rushes and sedges. It really is spectacular when massed, giving a needed burst of color in late summer and fall. Sweetscent is easy to start from fresh seed.

Sweetscent is widely used medicinally in Caribbean countries. A tea made from the leaves stimulates perspiration and urination. It is used to combat stomach cramps and as an eyewash for itchy eyes due to hay fever. The tea is a stimulant that works as a vasodilator (increases the size of small blood vessels). It should not be used in excess or in persons prone to migraines or by pregnant women

. The fragrant dried leaves have been used as an insect repellant. They would make a good addition to old-fashioned sachets. Dried flowers are also attractive in floral arrangements.