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Text and photographs protected by Copyright © Adrian Hoskins 2007, and must not be published in part or in whole elsewhere without prior written permission from the author.
Butterflies of the Andes
 
Great Tiger-mimic
Pterourus zagreus DOUBLEDAY, 1847
Family - PAPILIONIDAE
subfamily - PAPILIONINAE
Tribe - PAPILIONINI
 
 introduction | habitats | lifecycle | adult behaviour
 
Pterourus zagreus zagreus, male, Rio Frio, Venezuela
 
Introduction
 
The genus Pterourus includes 19 largish Swallowtail butterflies. Amongst them are the huge Jamaican endemic P. homerus, and the Tiger Swallowtails multicaudata, eurymedon and glaucus, the latter of which occurs as far north as Alaska.
 
Most members of the genus look like fairly typical Swallowtails - tailed, marked with creamy-yellow bands on a black ground colour, with red submarginal lunules on the underside hindwings. P. zagreus is totally different in appearance, and could easily be mistaken for a large Danaine, but a closer look reveals the anatomical features that identify it as a member of the Papilionidae - most noticeably the six long stilt-like legs, and the recurved antenna tips.
 
Pterourus zagreus is probably a mimic of the highly toxic Danaine Lycorea halia. Both species are members of the "Tiger complex", a mimicry-ring comprising of many dozens of dark butterflies, all marked with orange and cream. The majority are toxic or highly distasteful to birds, and are mimicked by smaller numbers of palatable species. Birds leave the palatable species alone, having learnt that tiger marked butterflies are in most cases distasteful.
 
The butterfly occurs in various geographical forms, from Costa Rica to Bolivia.
 
Habitats
 
This is primarily a butterfly of pre-montane cloudforests, occurring at altitudes between about 800-1600m.
 
Lifecycle
 
This appears to be unrecorded. The early stages of several other members of the genus Pterourus are well documented however, and are likely to be applicable to zagreus :
 
The eggs are round, and laid singly on the foodplants.
 
The caterpillars when young resemble a bird dropping. When fully grown they are green, beautifully marbled with pink and brown. The thoracic segments are marked with a pair of "false eyes" with black and white pupils. If threatened the larva immediately withdraws it's head, causing the thoracic segments to distend, and thereby greatly magnifying the size of the "eyes". The resulting snake-like appearance is probably sufficient to startle or frighten a small predatory vertebrate.
 
Adult behaviour

 

Males are usually seen in one's and two's, drawn to places where unsurfaced forest roads are forded by little mountain streams. If disturbed they fly up to perch on foliage at a height of about 5 - 10 metres, but return to drink at the water's edge once the threat has passed.

 

 

 
 
Text and photographs protected by Copyright © Adrian Hoskins 2007-2008, and must not be reproduced or published in part or in whole elsewhere in any form without written permission from Adrian Hoskins. Breach of copyright will be pursued by litigation.
 
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