Silba adipata McAlpine

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Author : François DROUET.
Photographs : François DROUET.
(unless indicated).
All rights reserved.

 

 

General description

 

 

 

I must mention for those who are searching for ancient documentation about the Black Fig Fly (Silba adipata McAlpine,1956) that, in all documents prior to 1956, the species is known as Lonchaea aristella Beck., 1903. It is therefore important to successively launch the Internet requests with the two Latin names.

Do not miss the major study (morphology, biology, fig infestation...) of the Black Fig Fly published in 1917 by Filippo SILVESTRI (1873-1949). The latter was an Italian entomologist who taught at the University of Roma, then directed the institute of zoology within the Higher School of Agriculture of Portici (to the immediate south-east of Napoli), of which he was also the director. Reference: SILVESTRI F., 1917, Sulla Lonchaea aristella Beck. (Diptera : Lonchaeidae) dannosa alle infiorescenze e fruttescenze del caprifico e del fico, Bollettino del Laboratorio di Zoologia Agraria in Portici, vol.12, pp. 123 -146.
 

Filippo SILVESTRI (1873-1949). Italian entomologist.

Filippo SILVESTRI (1873-1949).
Credit:
Wikipedia.
 

I provide below a general description of the Black Fig Fly, according to the following plan : appearance, size.

 

BLACK FIG FLY APPEARANCE

 

IDENTIFYING THE BLACK FIG FLY

Below, two photographs showing three black fig flies consuming latex on a green fig tree twig of the year. We can note that the photographs allow lateral, dorsal and three-quarter views of the Black Fig Fly. Characters to keep in mind: very small size (to be compared to that of the attachment point of the torn leaf petiole), uniform black color, brick red eyes, stocky appearance, wings position (closed and overlapping).
 

Three black fig flies consuming latex on a green fig tree twig of the year.

Three black fig flies consuming latex on a green fig tree twig of the year.

 

Three black fig flies consuming latex on a green fig tree twig of the year.

Three black fig flies consuming latex on a green fig tree twig of the year.

 

PRESENTATION VIDEO

In the video below, Silba adipata McAlpine, which is very avid of latex, walks on a fig tree twig of the year that I coated with latex by rubbing the base of a torn leaf petiole over it.

 

Silba adipata McAlpine consuming latex spread over a fig tree twig of the year.

 

TWO PHOTOGRAPHS TO FAMILIARIZE US WITH THE BLACK FIG FLY

Below, the first photograph shows a male specimen, recognizable by the apex (terminalia) of the abdomen. The second photograph shows a female specimen, the end of the abdomen of which is not really visible, but recognizable by the wide interocular space (the one for the male being narrow).
 

Black Fig Fly (Silba adipata McAlpine) : male specimen.

Black Fig Fly (Silba adipata McAlpine, 1956) - male specimen.

 

Black Fig Fly (Silba adipata McAlpine) : female specimen.

Black Fig Fly (Silba adipata McAlpine, 1956) - female specimen.

 

BLACK FIG FLY FEMALE OVIPOSITOR

According to my observations, it is very rare to see on the fig tree a female with the ovipositor out, when it is not laying eggs.

But the female almost always exteriorizes the ovipositor before dying (when captured in a trap, for instance). This particularity makes easy the count of the females (ovipositor out) and the males (no visible ovipositor), when emptying the traps as part of a field experimentation. But this method is slightly approximate, because a very small part of the females do not release their ovipositor when dying. I did not precisely assess their proportion, but I think that it does not exceed 5 %.
 

Black Fig Fly (Silba adipata McAlpine) : a female with the ovipositor out.

Silba adipata McAlpine: a female with the ovipositor out.

 

BLACK FIG FLY SIZE

 

According to my observations and measurements, the common size (for the body, wings excluded) of the Black Fig Fly is 4 mm, but it exists a size variability for both sexes. The size of Silba adipata McAlpine is more or less the twice of that of Drosophila suzukii Matsumura (Spotted Wing Drosophila).
 

Black Fig Fly: common size for both sexes (4 mm).

Black Fig Fly: common size for both sexes (4 mm).
 

The female length (ovipositor excluded) varies from 3.5 to 5 mm. The length is often 4 mm, but the lengths of 3.5 mm and 5 mm are rather frequent.
 

Silba adipata McAlpine: the three sizes that can be observed for the female.

Silba adipata McAlpine: the three sizes that can be observed for the female.
(from the bottom to the top: 5 mm, 3.5 mm, 4 mm (2 females).

 

Silba adipata McAlpine: three female specimens (on the right: 4 mm; on the left: 3.5 mm).

Silba adipata McAlpine: three female specimens (on the right: 4 mm; on the left: 3.5 mm).
 

The female specimens with a length of 5 mm are less frequent that the 4 mm long specimens, but are not rare.
 

 Silba adipata McAlpine: female specimen with a length of 5 mm.

Silba adipata McAlpine: female specimen with a length of 5 mm.
 

The male length varies from 3.5 to 4.5 mm. The length is often 4 mm, but the length of 3.5 mm is frequent (that of 4.5 mm is not frequent). I found males with a length of 5 mm but they are very rare. I only captured two male specimens of this length.
 

Silba adipata McAlpine: two male specimens (on the left: 4.2 mm; on the right: 3.5 mm).

Silba adipata McAlpine: two male specimens (on the left: 4.2 mm; on the right: 3.5 mm).

 

 Silba adipata McAlpine: male specimen with a length of 5 mm (note the end of the abdomen).

Silba adipata McAlpine: male specimen with a length of 5 mm (note the end of the abdomen).
 

As it exists an overlap between the male and the female lengths, the size cannot be used to differentiate the sexes for the Silba adipata McAlpine species (the two differentiation criteria are the end of the abdomen and the interocular space - wide for the female and narrow for the male).

 

 

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