SOUTH AUSTRALIAN BUTTERFLIES

Taractrocera ina Waterhouse  (Ina or No-brand Grass-dart)

 

Life History Notes on the No-brand Grass-dart, Taractrocera ina (Waterhouse, 1932)
Lepidoptera: Hesperiidae -
Wesley Jenkinson

ina_fem.jpg (62096 bytes)

Egg laying female

This small butterfly, also known as the Ina Grass-dart, mainly occurs along much of the coastal and sub-coastal regions of Queensland. The species is relatively common but localised and is found amongst grasses in eucalypt open-forest (Common and Waterhouse 1981) and open woodland. The adults visit and will breed in suburban gardens in Southeast Queensland providing suitable habitat and host grass is established nearby (or is growing as weeds in unmown lawns). Several exotic grasses are known as hosts, however the native hosts (if any are known) remain unpublished. At Beaudesert in Southeast Queensland I have found eggs and larvae on a known exotic host, Lemon Grass (Cymbopogon citrata) (Common and Waterhouse 1981) and recently in 2009 I confirmed larvae found feeding naturally on exotic Paspalum Grass (Paspalum dilatatum) (Wesley Jenkinson, in Moss 2010).

Like many of Queensland’s small sized grass-darts the adults can be difficult to separate. In comparison with other grass-darts in the Suniana and Ocybadistes genera the Taractrocera genus have more flattened and rounded (spoon shaped) antennal clubs. The sexes can also be tricky to identify with the males having no forewing sex brand. The females have slightly more rounded wing termens and wider abdomens compared to males.

Within Queensland, individual specimens vary minimally in the extent and intensity of the orange markings but the underside occasionally has a greenish tinge.

ina_f_UPS.jpg (19089 bytes)ina_m_UPS.jpg (11664 bytes)ina_m_UNS.jpg (11060 bytes)ina_f_UNS.jpg (10858 bytes)
Images left to right:  male, female, male underside, female underside
Wingspans for the pictured adult specimens are males 24mm and females 25mm

Adults have the typical erratic rapid ‘skipper’ flight and frequently settle on grass or low-lying vegetation to bask in sunshine. The males are territorial and can be observed in swift chases with other males, often returning to settle on the same perches. The adults of both sexes are readily attracted to a wide range of small native and exotic flowers.

During a hot day in January at Beaudesert a female was observed briefly landing on the upperside of a host grass leaf in dappled sunlight. She then walked with the wings closed around the leaf margin to the underside of the leaf and laid a single egg, a short distance was then flown and she again settled on the upperside of another grass leaf to rest.

ina_egg.jpg (5045 bytes)
Freshly laid egg

The eggs are dome shaped, approximately 1.0 mm wide x 0.6mm high, smooth, white when laid but changing to creamy-white after two days.

The egg was collected and was raised in captivity to an adult on Paspalum dilatatum. The tiny larva consumed the eggshell shortly afterward emergence. Later it proceeded to form a cylindrical shelter near a leaf tip of the host plant. Making small transverse cuts from the outer leaf edge towards the midrib, it then curled the leaf margin inwards using silk to form the shelter. Later when feeding occurred the leaf was eaten from both sides of the margin and stopped at the leaf midrib. This caused the cylindrical shelter to hang (similar habit described in Braby 2000). Several silk lined shelters were created throughout the larval duration and typically the larva emerged at dusk to feed. The final shelter created initially measured 200mm in length. The fifth instar remained in the final shelter and before pupation it stitched the posterior end of the shelter closed leaving a small opening remaining at the anterior end (the adult emergence hole).

ina_1st_instar_la.jpg (10558 bytes)

1st instar larva

ina_2nd_instar_la.jpg (27462 bytes)

2nd instar larva

ina_3rd_instar_la.jpg (37722 bytes)

3rd instar larva

ina_4th_instar_la.jpg (83462 bytes)

4th instar larva

ina_5th_instar_la.jpg (46476 bytes)ina_5th_instar_la_head.jpg (33111 bytes)

5th instar and head closeup

The larva completed five instars and attained an approximate length of 25mm.

ina_pupa_new.jpg (42197 bytes)

New pupa in opened shelter, dorsal view

ina_pupa_old.jpg (26458 bytes)

Mature pupa, lateral view

The pupa measuring 16mm in length was located loosely in the final shelter and was very finely covered in a white waxy powder.

An egg laid on 23rd January 2009 hatched in 3 days. The larval duration was 41 days and pupal duration eight days. The adult emerged in March, 52 days after eggs were laid (oviposition).

Within the new boundary of the Scenic Rim Regional Shire south of Brisbane, I have records of the adults during the hotter months from October to March. At this locality there are probably two generations completed during the year.

So next time you are in the garden, spend some time looking for this fine species as it may be present!

References:
Braby, M.F., 2000. Butterflies of Australia – Their Identification, Biology and Distribution. vol 1. CSIRO Publishing, Melbourne.
Common, I.F.B. & Waterhouse, D.F., 1981. Butterflies of Australia (revised edition). Angus & Robertson Publishers, Sydney.
Moss, J.T. 2010. Butterfly Host Plants of South-east Queensland and Northern New South Wales. 3rd rev. edition, Butterfly and Other Invertebrates Club Inc., Brisbane.

 

This article was originally published in Metamorphosis Australia
the Magazine of the Butterfly & Other Invertebrates Club.
No 60, March 2011. http://www.boic.org.au, copyright, all rights reserved.