SOUTH AUSTRALIAN BUTTERFLIES
Data Sheet

Argynnina cyrila Waterhouse and Lyell   (Forest Xenica)

Interesting aspects:  This small butterfly is the first satyr to start flying in the season in the southeast of mainland Australia.  It has a fast but erratic flight.  The sexes are similar in appearance, but can be readily distinguished by the large silky grey sex brand present in each forewing of the males, which occurs transversely across the centre of the wing upperside.  The forewing in the males is also noticeably narrower than in the females.  Their uppersides have bold orange and black patterns similar to the Oreixenica butterflies although the former are more closely related to the Heteronympha satyrs.  The underside of the hindwing has a variable pale cryptic brown pattern, which makes the butterflies difficult to distinguish from dead plant debris when they are settled on the ground among grasses, particularly in dappled forest light.  However, these butterflies usually settle with wings open and they then become more obvious.

Males will establish territories in sunny areas by perching on bracken, low bushes or on higher canopy.  They also avidly hilltop if one is present nearby to the breeding grounds.  Females are more often seen on or near the ground in sunny areas of the forest, from where they undertake egg-laying forays.

The butterflies are normally very timid and it takes considerable care to get near them.  Once startled they usually fly off to a higher vantage point or even up into the tall Eucalyptus canopy, although females may only fly off to another low position. 

Life History

Larval food-host:  Native and introduced grasses including Poa species such as P. meionectes, Microlaena stipoides (weeping rice-grass) and possibly Tetrarrhena spp (rice-grasses) (Poaceae).  The larvae feed on the hostplant leaves.  In captivity they will eat some introduced grasses, including *Brachypodium distachyon (false brome), *Cynodon dactylon (couch), *Poa pratensis (Kentucky blue-grass) and *Ehrharta erecta (panic veldt grass).

Eggs:  Small, pale green, thin shelled, nearly spherical, shining but with a series of very fine, indistinct vertical ridges that are more obvious apically but which do not extend onto the large apical area.  The latter has a fine reticulated pattern and in the centre is the micropylar area, which is raised like a pimple.  Usually laid singly on the hostplant, or sometimes on other plants or debris adjacent to the hostplant.  In captivity where there is less distraction, the females will lay eggs in small groups on the leaves or in long strings along the hostplant stems.  Larva development within the egg commences immediately after being laid, and larvae begin to emerge in about 8 days in warmer areas but may take up to 15 days in cool regions.  When ready to emerge, the larva incompletely cuts out a large circular area at the top of the egg, leaving a small uncut portion, and then pushes the top out like a hinged lid.  The egg-shell (chorion) is then eaten by the larva.  In captivity in Adelaide eggs had completed hatching by late November.

In the wild the females lay eggs by first fluttering slowly over the ground to detect the hostplant, then they usually drop onto or near the hostplant to quickly lay an egg before flying off again.

Larvae:  The first instar is initially pale yellow with an indistinct whitish, broad longitudinal dorsal line, and whitish narrow subdorsal and lateral lines.  The head is large, finely rugose, brownish black with some long dark hairs, rounded but divided dorsally and with a pair of vestigial dorsal horns.  The neck area is reddish and there are two dark, elliptical shaped prothoracic plates.  There is a pair of vestigial posterior protrusions and the posterior anal plate is pale brown.  There are longitudinal series of black, knobbed hairs (setae) along the body that are longer dorsally, and which emanate from simple smooth, pale coloured conical bases.  The knobs are sticky, presumably for defensive reasons.  After eating the green leaves of the hostplant, the larvae gradually become greenish accentuating a narrow dark green longitudinal dorsal line. 

When disturbed, unlike other South Australian satyrs, the early instar larvae raise the anterior parts of their bodies.  They will swing their raised heads back onto any small predator or disturbance that occurs along their bodies. 

The second instar is similar to the late first instar, but the head is rounded, granular, dark brown, paler laterally and with some obscure pale frontal markings.   There is a pair of short granular dorsal horns.  The head and horns are hairy with each hair protruding from a hard, smooth conical base of variable colour, that are larger on the lateral parts of the head, and a further large pair occur dorsally posterior to the horns.  The tips of the horns also have a single long hair emanating from a reddish-brown base.  The body is setaceous with dark coloured hairs usually un-knobbed and emanating from white coloured bases.  A short pair of protrusions occur posteriorly, coloured white laterally as an extension of the white subdorsal line, but pinkish brown internally similar to the anal plate. A pattern of dark green, elongate diamond shapes, combined with the dark dorsal line, occur dorsally along the body that become more prominent as the larva grows. The white subdorsal line is wavy matching the dorsal diamond pattern.

Larvae feed at night, resting during the day hidden in the lower, cooler parts of the host grass.

The third instar is similar to the second instar but can be green or brownish-green.   There are a lateral series of black dots in the position of the spiracles, and again dorsally where they occur at each junction of the diamond in the dorsal pattern.   The head is similar but has more vivid colours with a prominent white frontal pattern, the rear side areas are pale brown, the horns are reddish brown, tipped with a white conical hair base.  The lateral conical hair bases continue to grow as the head enlarges and are white coloured, the large dorsal pair are reddish brown.  The mandibles are red.  The posterior end is forked.  The fourth instar is similar to the third instar but is brown coloured, darker laterally. The dorsal 'diamond' pattern is now very conspicuous, except the dark coloured diamonds have now changed their diamond shape with the posterior end of the diamond being pointed while the anterior end is rounded.  The dorsal pattern is also now reinforced with a large posteriorly pointing, dark brown V shape that combines with the posterior edge of each 'diamond'.

The fifth and final instar is cylindrical shaped, 22-28 mm long, being fatter in the middle, and the lateral edge is slightly flanged.  Only brown larvae have been recorded, of variable colour intensity from pale to very dark brown.  Pale larvae are darker lateral to a pale zig-zag subdorsal line, and there is a further pale lateral line.  There is a very conspicuous, darker brown, combined 'diamond' and V shaped pattern along the dorsal area similar to the fourth instar, with each lateral point of the diamond extending to the subdorsal area. There is a prominent short forked tail protuberance, coloured white laterally as an extension of the pale subdorsal line, but darker brown internally similar to the diamond pattern.  The body is without long hairs, but supports numerous short pointed secondary setae imparting a rough scabrous appearance.  The head is large, rounded, rugose with numerous short hairs, with a similar but more obscure pattern compared to the fourth instar, generally brown coloured with a darker brown peripheral band.  There is a prominent pair of orange-brown coloured, short, rugose, hairy dorsal horns, with a large pale coloured, smooth conical hair base protruding from the top of each horn.  Similar large, smooth hair bases occur peripherally around the perimeter of the head; five pale orange coloured bases occur on each side of the head, a white base occurs on each side of the head frontally, and an orange pair occur dorsally on the top of the head posterior to the horns.  Older larvae tend to be messy and wasteful feeders, eating through the leaves about halfway, letting the outer half drop to the ground before eating down the lower half.

The larvae can develop very rapidly, and in captivity in Adelaide (from eggs laid in mid-November) they required only 8 weeks before pupation started in mid-January, but pupation continued through to early March.  Elsewhere, it has been reported that 10 weeks were required in central Victoria and 13-20 weeks near Sydney to complete the larval period.

Pupae:  Short, stout, compact, 10-12 mm long, suspended head downwards by the cremaster, the portion of abdomen extending beyond the wings is considerably shorter than the wings and head combined.  The ventral side and wings are essentially smooth, but the dorsal side has a granular rough appearance.  There is a subdorsal row of short, smooth, rounded conical protuberances along the abdomen and thorax, the thorax is arched and keeled dorsally with a few obscure knobby protrusions, the wing bases strongly protrude, the wing junction with the thorax is weakly keeled and is straight looking from above, the head is wedge shaped anteriorly and weakly divided, the abdomen is arched dorsally and bluntly curves posteriorly and tapers to a moderately long, stout, black cremaster.  Pupae are cryptically patterned in brown, reddish brown, brown-black and greys, the abdomen is mostly reddish brown, the inner-margin half of the wing area is usually pale or whitish, while in dark patterns there is sometimes a distinct large white spot laterally on the wing termen.  The intensity of the pattern varies from pale to dark, looking like a small piece of fungus infested wood or sometimes even like a piece of charcoal.   The pupa is either suspended from the hostplant deep within the plant clump near the ground, or the prepupa leaves the plant to seek more favourable environmental conditions elsewhere.

The pupa cuticle is very thick.  Not withstanding this, the pupae likely have a high susceptibility to desiccation during dry periods or from diseases or field chemicals during the pupal torpid stage over winter.  In captivity very few pupae survive over winter, which would suggest they require very demanding conditions for survival and may explain why the adult flight time and numbers are so variable.

Flight period:  Only one brood a year.  In southwest Victoria it has a short flight period from about late October to late November.  However, the emergent period varies from year to year probably dependant on the previous seasons as to how dry it was, and numbers flying also vary from prolific to virtually absent.  The males emerge earlier than the females.  It overwinters as pupae.

Distribution:  The butterfly has yet to be recorded in South Australia.  It occurs in southwest Victoria, 35 km from the SA-Vic border, and so it is expected that this butterfly may eventually be found in S.A., either as vagrants or small resident populations.  The range of the butterfly extends throughout the moist montane and cool coastal areas of Victoria, NSW and southeast Queensland.

Habitat:  The butterfly requires cool, damp (often leech prone), shady, temperate forest areas receiving more than about 750 mm of annual rainfall, and having its grass hostplants in the understorey remaining in a green condition all year round.  It requires open sunlit areas and the understorey to be open and not congested by bracken and tea-tree, or similar plants.  Its original understorey habitat was probably the Poa and Tetrarrhena grasslands, which require moist conditions.  The butterflies are more often encountered in montane areas with deep moist valleys where the butterflies can retreat on very hot days, and where the hostplants are more likely to remain in a green condition.  The butterflies and their early stages also seem to best tolerate average maximum temperatures of less than about 20 C.

Conservation Status:  Likely to be extremely rare and localised if found in South Australia, although in the adjacent areas of Victoria where there has been a better retention of native forests, the butterflies can sometimes be locally common during good seasons.

Threats:  Suitable cool, moist, tall forest habitat with Poa/Tetrarrhena understorey is now extremely rare in SA.  Such habitat was long ago fragmented and degraded, or turned into pine plantations.  The remaining areas are now under constant threat from bushfires and understorey degradation from the invasion of bracken.   Bushfires, drought, over grazing by kangaroos, and urban and forestry expansion would likely be the main threats under present conditions.

Conservation Strategy:  If colonies of the butterfly were found, then they would need to be monitored to prevent invasion by choking exotic weeds to their habitat, and to prevent over grazing of the Poa/Tetrarrhena understorey by kangaroos although some grazing is probably essential to stop the grass from getting too rank.   Toxic agricultural and forestry insecticides and weedicides used in adjacent areas would need to be judiciously applied, particularly those sprays distributed by aerial means.

 

Author:  R. GRUND, copyright 15 November 2002, all rights reserved.
Last update 20 March 2008.