Singing the Blues - Butterfly Gear

The Lepidoptera Log - by Steve Woodhall

Singing the Blues

Spotting the 'tinies'

The family Lycaenidae (the so-called ‘Gossamer-winged butterflies’) includes a group commonly referred to as ‘blues’ because many have blue upper wings. They belong to the subfamily Polyommatinae. Identifying them can be challenging since their upper wings often lack obvious distinguishing marks. While many display shades of blue, others are grey, brown, or even black.

Most members of this group are small, with some among the tiniest butterflies in the world, boasting a wingspan as little as 10mm—smaller than a pinkie nail. Their habit of flying close to the ground or settling on low plants can make observation tricky, sometimes requiring you to kneel for a closer look. A telephoto macro lens is helpful in these situations.

Capturing a photo with their wings open may assist identification, but since many look similar from above, sometimes only the wing edges offer clues. Thankfully, the patterns of spots and lines found on the undersides of their wings are usually unique to each species. With a Field Guide and some experience, it’s possible to identify them using these features.

This online guide will introduce some of the more often encountered species, offering insight into the fascinating world of the ‘blues’. There are many of them, so we’ll break them into small groups. Let’s start with ones you might find in your garden.

The Three ‘Z’s (this rhymes if you’re American!)

The commonest ‘blues’ can be the hardest to tell apart. The African Grass Blue Zizeeria knysna, African Clover Blue Zizina otis antanossa, and Tiny Grass Blue Zizula hylax are extremely widespread and are a good place to start. Even their scientific names sound similar! These butterflies all share blue colouring on their upper wings, while their lower wings are pale grey marked with dark spots and lines bordered in white. They are all slow, weak, low flying insects.

The African Grass Blue – Zizeeria knysna knysna is one of the commonest butterflies in Africa and gets its English name from the way it is often found in lawns where its host plants grow, often as weeds. It’s a widespread butterfly that’s covered elsewhere as a garden species on the site. It’s found all over Africa, Madagascar, Arabia, the Middle East, southern Europe, as well as Asia and Australia. It’s a very small butterfly; males vary from 18-23mm, females 21-26mm.

Like most of the Polyommatinae its upper side is fairly plain – violaceous blue in the male with a broad grey-brown border, and in the female, mainly grey-brown with a patch of blue at the base of the forewing, and a dull blue hindwing with a broad grey-brown area towards the costa (leading edge). The blue varies in shade and intensity as the angle of light changes. In strong sunlight it appears more iridescent.

It’s easy to confuse with its close relatives the African Clover Blue and Tiny Grass Blue. Its underside sets it apart from these. Like them, its ground colour is pale grey. The differences are in the patterns of lines and spots, and the shapes of those features. The intensity of these can vary as shown above, and sometimes requires close inspection to make out the details.

The things to watch out for are the shape of the postdiscal series of hindwing dark spots, and the shape of the dark spot below the apex of the forewing (arrow 1). The forewing underside has a black spot at the base of the cell (arrow 2) that is missing in the other two species. As shown above, the postdiscal hindwing series follows a regular, semicircular pattern, and the forewing spot is more-or-less circular.

The courting pair at top left are on a patch of a host plant, Creeping woodsorrel, Oxalis corniculata. This is a widespread lawn weed in the warmer parts of the world. So, if you use weedkiller on it, the butterfly will likely disappear.

Other host plants are Devil-thorn Tribulus terrestris, Cape Pigweed Amaranthus thunbergii, and African Purslane, Zaleya pentandra. It also uses plants in the Pea family, Fabaceae, like Lucerne, Medicago sativa.

The African Clover Blue Zizina otis antanossa is less common in South Africa compared to the African Grass Blue, occurring mainly on the eastern side and as isolated colonies in the southern Cape. Across Africa, it appears widely except in dry regions. Subspecies antanossa inhabits Africa whilst other subspecies extend across Asia, Japan, Indonesia, Australia, New Zealand, and the Pacific Islands. Like the African Grass Blue, this butterfly relies on a widespread weed, ‘Sweethearts’ (Desmodium incanum), also known as creeping beggarweed, Spanish clover, Spanish tick-trefoil, or hitchhikers—a South American invasive species. Its indigenous host plants in Africa are species of Indigofera (Indigos).

On its upper wings, the African Clover Blue displays a brighter, more metallic silver-blue shade than the African Grass Blue, with less violet tint and broader, less distinct grey-brown borders. The hue varies considerably as the angle of viewing light changes. The margin of the hindwing features a sequence of dark spots edged by blue. Female butterflies show an even more vivid blue, with a noticeable wavy pale whitish blue line along the hindwing edges. It’s very slightly larger, on average, than the African Grass Blue. Males vary from 20-24mm wingspan, females 21-28mm.

Identifying this butterfly isn’t always easy, since the blue’s hue shifts with the viewing angle. However, the underside offers a more reliable clue: while the background colour is often a warmer grey than that of the African Grass Blue, this trait can be inconsistent as shown. The roundness of the dark spot below the forewing apex (arrow 1) isn’t always consistent either, sometimes appearing arched. The key indicator is found in the arrangement of the spots—the postdiscal series on the hindwing does not form a regular, semicircular curve as it does in African Grass Blue and Tiny Grass Blue. Specifically, the spot in area R5 of the hindwing (arrow 2) sits farther inward toward the base, which reliably separates the African Clover Blue from the African Grass Blue.

The Tiny Grass Blue Zizula hylax is the smallest among this group of similar species. The wingspan varies from 17mm in small males to 25mm in larger females. Like the other two ‘Z’s it has an extensive geographical range. It’s found almost everywhere in Africa, the Indian Ocean islands, the oriental region, Asia, Australasia, and some of the Pacific islands.

Its host plants are mostly in the Acanthaceae: Dyschoriste, Justicia, and Ruellia species as well as Sticky Acanth, Phaulopsis imbricata as shown. Males are notably diminutive, often no larger than a pinkie nail. The upper surfaces of males display a vivid sky blue colour bordered by a comparatively narrow grey-brown margin, while females typically exhibit a dark grey colouration, occasionally with a hint of blue on the forewings.

There is a degree of size overlap between the largest Tiny Grass Blues and the smallest African Grass or Clover Blues, which can complicate identification based solely on their upper sides. Nevertheless, the distinctive dark markings found on the undersides facilitate reliable differentiation after some experience. Key identification features include an apical dark mark on the tip of the forewing resembling a curved line rather than a spot (arrow 1), two additional dark spots (arrow 2) along the leading edge of the forewing, and an evenly curved black marginal line on both wings (arrow 3), unlike the wavy grey line seen in the other two species. This is outlined in white on both sides, making it more conspicuous.

Further distinguishing characteristics of Tiny Grass Blues are their more elongated, elliptical wings and rounded wing tips. It is an even weaker flyer than the African Grass or Clover Blues, flying low down with rapidly beating wings but never travelling far. When at rest, these butterflies frequently sway from side to side, causing the wings to move rhythmically—a behaviour that has led to their colloquial designation as ‘Waggle Wings‘.

In my next blog on this subject, we’ll look at another group in the Polyommatinae – the ‘Pies and Pierrots’.

African Grass Blue courting pair (♀ R)

African Grass Blue ♂

African Grass Blue ♂

African Grass Blue ♀

African Grass Blue ♀

African Grass Blue ♂

African Grass Blue ♂

African Grass Blue with identification pointers

African Clover Blue ♂

African Clover Blue ♂

African Clover Blue ♀

African Clover Blue ♀

African Clover Blue mating pair

African Clover Blue ♀ on 'Sweetheart' flower

African Clover Blue ♂

African Clover Blue with identification pointers

Tiny Grass Blue ♂

Tiny Grass Blue ♂

Tiny Grass Blue ♀

Tiny Grass Blue ♀

Tiny Grass Blue ♀

Tiny Grass Blue ♀ on Sticky Acanth

Tiny Grass Blue ♀

Tiny Grass Blue with identification pointers

Tiny Grass Blue on host plant Sticky Acanth

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