eastern hornet fly

(Spilomyia longicornis)

               
Conservation Status

IUCN Red List

not listed

eastern hornet fly

NatureServe

NNR - Unranked

Minnesota

not listed

Occurrence

Uncommon

Flight/Season

Late May to late October

Habitat

Hardwood forests, often on hilltops

Size

Total Length: ½ to (12.4 to 16.2 mm)

          Photo by Alfredo Colon
 
Identification

Eastern hornet fly is a medium-sized, wasp-mimicking, flower fly. It occurs in the United States east of the Great Plains, and in Ontario and Quebec, Canada. Minnesota it is at the western extent of its range, and it has been recorded only in and around the Metro region of the state. Adults are found from late May to late October hovering around flowers in hardwood forests, often on hilltops. Larvae are found in deep rotholes in trees. A rothole is a cavity formed at the site of a wound as the result of fungal and bacterial action. A deep rothole is a rothole that does not heal. The water inside is mostly from the vascular system of the tree, not from rain, and is reddish-brown, not clear.

Eastern hornet fly mimics vespid wasps (Family Vespidae) in both appearance and behavior, but unlike wasps it cannot sting. The face is yellow and straight, not concave. The lateral parts of the head (gena), equivalent to the cheeks, are yellow. A black line separates the face and gena. The antennae are are black and short. They have three segments with a large, brownish-yellow bristle (arista) on the third segment. The second segment is elongated, much longer than wide. The structure of protruding mouthparts (proboscis) is short and fleshy. There are two large compound eyes on the sides of the head and three small simple eyes (ocelli) in a triangle on the top of the head. The compound eyes are dark brown with an obvious yellow pigmented pattern that helps to disguise the large eyes. On the male the compound eyes meet at the top of the head. On the female they do not meet, and the black lines between the face and gena taper and converge approaching the ocelli, becoming a single thin brown line at the front ocellus.

The thorax is black with yellow markings. The large exoskeletal plate (scutum) covering the middle segment of the thorax has two pairs of yellow spots on the front margin, a yellow line on each side from the rear margin that bends inward at the transverse suture, and a pair of oblique yellow lines at the rear margin that form an inverted V. The small plate covering the upper rear portion of the thorax (scutellum) is black on the basal half with a broad yellow margin around the sides and rear.

The abdomen has four segments, and each segment is covered by a hardened exoskeletal plate (tergite). Tergite 1 is entirely black. Tergites 2, 3, and 4 are black with a yellow band about one quarter the distance between the front and rear margins (anteromedial band), a yellow band on the rear margin, and yellow lateral margins. The black area between the two bands is much broader than either band. The front band on tergite 2 is complete but may be shallowly notched in the middle. On tergite 3 the front band is deeply notched or slightly separated in the middle. On tergite 4 the front band is noticeably separated in the middle. On the male the rear band on tergite 4 is straight, not curved. The rear band on all tergites may be complete or have a thin black line in the middle. All of the yellow bands are hairless.

The wings are mostly clear but the front third is darkened. The small, knob-like structures on each side of the thorax (halteres) used for balancing in flight are yellow. There is a spurious vein between the radius (R) and media (M) veins. The cross-vein that runs between the R and M veins is strongly oblique. The anal cell is long and is closed near the wing margin. The R5 and M2 cells are also closed. The radial sector vein (Rs) has 2 branches.

The legs are mostly yellow. The third segment (femur) of the hind leg has an unbranched spur near but not at the tip. The fourth segment (tibia) of the front leg is mostly black, yellow just at the base. The last part of the leg, corresponding to the foot, has 5 segments. It is black on the front legs, yellow on the middle and hind legs.

 
Similar
Species

 

 
Larval Food

 

 
Adult Food

Pollen and nectar of goldenrods, asters, and possibly other plants whose flowers produce large amounts of pollen.

 
Life Cycle

 

 
Behavior

When threatened it will wave its black front legs in front of its head, mimicking the antennae of a wasp, and flutter its wings, mimicking the behavior of a wasp.

 
Distribution Distribution Map  

Sources: 24, 27, 29, 30, 82, 83.

 
Comments

 

 
Taxonomy

Order:

Diptera (gnats, mosquitoes, true flies)

 

Suborder:

Brachycera (circular-seamed flies, mouches muscoïdes, muscoid flies, short-horned flies)

 

Infraorder:

Muscomorpha

  no rank:

Eremoneura

  no rank:

Cyclorrhapha (circular-seamed flies)

 

Section:

Aschiza

 

Superfamily:

Syrphoidea

 

Family:

Syrphidae (hover flies)

 

Subfamily:

Eristalinae

 

Tribe:

Milesiini

 

Subtribe:

Milesiina

 

Genus:

Spilomyia

 
Synonyms

Spilomyia banksi

 
Common
Names

eastern hornet fly

 

 

 

 

Glossary

Arista

A large bristle on the upper side of the third segment of the antenna of a fly.

 

Femur

On insects and arachnids, the third, largest, most robust segment of the leg, coming immediately before the tibia. On humans, the thigh bone.

 

Gena

In insects, the area below the compound eye. In birds, the feathered side (outside) of the under mandible; the area between the the angle of the jaw and the bill.

 

Halteres

In flies: a pair of knob-like structures on the thorax representing hind wings that are used for balance.

 

Ocellus

Simple eye; an eye with a single lens. Plural: ocelli.

 

Proboscis

The protruding mouthpart(s) of a sucking insect.

 

Scutellum

The exoskeletal plate covering the rearward (posterior) part of the middle segment of the thorax in some insects. In Coleoptera, Hemiptera, and Homoptera, the dorsal, often triangular plate behind the pronotum and between the bases of the front wings. In Diptera, the exoskeletal plate between the abdomen and the thorax.

 

Scutum

The exoskeletal plate covering the forward (anterior) part of the middle segment of the thorax in some insects.

 

Tarsus

On insects, the last two to five subdivisions of the leg, attached to the tibia; the foot. On spiders, the last segment of the leg. Plural: tarsi.

 

Tergum; tergite

The upper (dorsal), hardened plate on a segment of the thorax or abdomen of an arthropod. Plural: terga.

 

Tibia

The fourth segment of an insect leg, after the femur and before the tarsus (foot). The fifth segment of a spider leg or palp.

 

 

 

 

 

       
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Alfredo Colon
       

I really love its psychedelic eyes.

  eastern hornet fly   eastern hornet fly
       
  eastern hornet fly    
       

A lovely Bee Mimic Fly

  eastern hornet fly   eastern hornet fly
       
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Other Videos
 
  Syrphid Fly (Spilomyia longicornis) on Eupatorium altissimum (Asteraceae) [125] Scene#023 Sep16 2012
Nature Documentaries
 
   
 
About

Jun 14, 2016

A syrphid fly (Spilomyia longicornis) pollinating/visiting flowers of Eupatorium altissimum (Asteraceae) in State Botanical Garden of Athens, GA.

http://bugguide.net/node/view/1174600

   
       
  Wasp-like hoverfly (Spilomyia longicornis) drinking nectar in flowers
GoTrails
 
   
 
About

Aug 31, 2019

Wasp-like hoverfly eating nectar & pollen in flowers | Spilomyia longicornis, Yellowjacket Fly | flower fly, syrphid fly, Syrphidae, Schwebfliegen, Stehfliegen, Schwirrfliegen, sírfidos, Syrphides, Syrphes, Sirfidi | mimicking, vs, wasp & bee | Wildlife, Animal Behavior, Nature, Insect Watching, arthropod | #GoTrails, #insect, #hoverfly, #insects, #syrphidfly, #flowerfly, #wildlife, #arthropod

   
       
  Behavioural mimicry in the hover fly Spilomyia longicornis (by Henri Goulet)
Chris Hassall
 
   
 
About

Sep 12, 2016

Behavioural mimicry occurs when an animal acts like another animal in order to deceive a third animal. In this video (taken by Dr Henri Goulet), you can see the fly wagging its wings in a manner characteristic of wasps, repeatedly tapping its abdomen against the flower (although flies cannot sting), and holding its dark forelegs in front of its head to mimic the longer antennae of wasps.

Research conducted at Carleton University, Agriculture and Agri-Food Canada and the University of Leeds has shown that only those hover flies that look most like wasps exhibit these kinds of behaviours.

See a similar video of the closely related S. fusca: http://youtu.be/CPTVgv_uj3s

   
       

 

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Alfredo Colon
8/22/2019

Location: Woodbury, Minnesota

I really love its psychedelic eyes.

eastern hornet fly


Alfredo Colon
8/19/2019

Location: Woodbury, Minnesota

A lovely Bee Mimic Fly

eastern hornet fly


     
     
 
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Created: 2/24/2020

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