Diogmites

Diogmites (Hanging Thieves) are charismatic predators, often hanging by one or two legs while they consume their prey. They are common throughout the state, but they can difficult to identify.

The available keys focus on the dark markings on the scutum (aka mesonotum or the top disc of the thorax), but there are other characters to check such as overall size, the shape of the abdomen, and markings on the side of the abdomen.

Below are the species known or thought to occur in Florida. Some species are variable, and I will update this page to include some of that variation.

Diogmites neoternatus

The most common species throughout most of the eastern United States is D. neoternatus. Thankfully this one is relatively easy to ID. The abdomen is orange and unmarked, and the top of the abdomen is pinched. Additionally, the stripes on the scutum are dark black, and the central stripe is undivided. The central stripe fades to red toward the pronotum (top of the thorax near the head) and rarely, but sometimes reaches the pronotum.

This is the only species in the area with an unmarked abdomen, and only D. neoternatus and D. ternatus have pinched abdomens.

Size: 20-30 (average 23.9) mm

Range: Throughout eastern U.S.

FL Range: Throughout

FL Season: late April-September

Diogmites crudelis

While variable in size, some individuals approach the largest robber flies we have at 48 mm. If you see a Diogmites and are struck by how massive it is, it’s probably D. crudelis. In this distinctive species, the stripes on the scutum are brown (not black), though they sometimes have narrow brown lines within them. The abdomen has “dark dorsal bands that are more or less interrupted mesally, lateroposterior angles of tergites golden.” (Artigas, 1966). Male genitalia yellow-haired.

Size: Huge, 26-48 (average 32.3) mm

Range: Southeastern US (NC, SC, GA, FL, AL, MS)

FL Range: Throughout

FL Season: May-October

Brad Moon’s photo series of D. crudelis from Louisiana is also helpful.

Diogmites salutans

Of all of the Florida species, this one may be the most tricky. The stripes on the thorax are brown (not black) and are “not strongly contrasting with color of disc.” The central stripe on the thorax is narrowly divided for its entire length. There is a black band on each abdominal segment. These are smaller than D. crudelis. Male genitalia black-haired.

Size: 20-25 (average 21.7) mm

Range: VA to FL, west to OK, AR, MS

FL Range: South to Manatee and Highlands Counties

FL Season: April-October

On this photo of a male D. salutans, you can clearly see the black hairs on the genitalia.

Diogmites properans

Central stripe on scutum is usually undivided and reaches the pronotum (front of thorax near the head). The markings on the thorax are velvety black, whereas they are brown on D. salutans. Black dorsal bands on abdomen, with “band sometimes becoming brownish or reddish mesally” (Artigas, 1966).

Size: 15-28 (average, 22.0) mm

FL Range: Most common in the panhandle, though they have been recorded south to Manatee County.

FL Season: May-September

Diogmites esuriens

Central stripe on scutum is divided and does not reach the pronotum (front of thorax near the head). Markings on thorax black, contrasting strongly with the pale disc color. Abdomen has slight constriction between second and third segments. Abdomen “tergites usually with a black oblique line on proximal angle, contrasting with the brown or golden background color, the posterior angles of tergites golden pruinose” (Artigas, 1966).

Size: 21-31 (average 25.0) mm

FL Range: Throughout

FL Season: late June-November

Diogmites misellus

Central stripe on scutum is undivided for most of its length, but it does not reach the pronotum (front of throax near the head) and shades to red toward the head. Markings on thorax are black. No black markings on abdomen.

Size: Smallest Diogmites in the genus, 16-23 (average 19.2) mm

Range: Eastern U.S.

FL Range: Panhandle and north Florida south to Alachua County

FL Season: June-August

Diogmites ternatus

This is supposed to be similar to D. neoternatus, but the central stripe on the scutum usually reaches the pronotum (top of thorax near the head), is undivided, and is entirely black. D. ternatus has a pinched abdomen with “posterior margin and lateroposterior angles of tergites golden pruinose,” meaning there should be markings on the side of the thorax like other Diogmites, but they aren’t black. Plus it’s a Cuban species with occasional records in the U.S. (Artigas, 1966). I haven’t encountered this one yet, and I’m not aware of any correctly identified photos online.

Range: Cuba, though there are records as far west as Texas and Kansas.

FL Range: Artigas (1966) lists a specimen from Jacksonville.

Diogmites discolor

Dark scutum (top of thorax) with black stripes, including a divided central stripe. Abdomen dark with silver spots on side of tergites (abdominal segments).

Size: 19-31 (average 24.0) mm

Range: Eastern U.S.

FL Range: It may occur in the western panhandle

Diogmites platypterus

Dark overall including top and sizes of thorax and abdomen with dark wings. Legs orange.

Size: 20.5-28.0 (average, 23.6) mm

Range: Midwest and eastern U.S.

FL Range: There is one October record from central Florida (Polk County) in the FL museum, though it may be mislabeled, and one published record from Gainesville. It may occur in the western panhandle.

Diogmites angustipennis

This species has not been recorded in Florida. It can only be distinguished from D. bilobatus via dissection. However, Barnes (2010) found that D. bilobatus has been recorded from California east to Louisiana, but D. angustipennis has several Mississippi and Alabama records. So D. angustipennis is more likely to turn up in the Florida panhandle. The markings and size vary widely, but both D. angustipennis and bilobatus lack distinct dark markings on the brown scutum (top of thorax).

Size: Varies widely. Male 16.5–28.9 mm (mean = 23.4 mm); female 15.2–29.9 mm (mean = 24.2 mm).

Season: April to late November throughout its range, though most specimens are July to September

References:

Artigas, J. N. (1966). The Genus Diogmites (Robber Flies) in Eastern United States (Diptera: Asilidae). Ohio J. Sci. 66(4): 401-421.

Barnes, J. K. (2010). Nearctic species related to Diogmites angustipennis Loew (Diptera: Asilidae). Zootaxa, 2545(1), 1-22.

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