BR. J. ENT. NAT. MIST., 7: 1994 



DO TORTOISE BEETLE PUPAE MIMIC LACEWING87 



Richard A. Jones 



13 Bel/wood Road, Nunhead, London SE15 3DE. 



At first, this question may seem rather strange; how could the stout, wingless, 

 wholly functional carapace of any coleopterous pupa resemble, in the slightest, 

 the delicate winged and lithe form of the Neuroptera? The answer, as I hope the 

 accompanying photographs show, is 'yes, when seen in profile'. I would argue that 

 this is not just coincidental, not an accident of light , and not a trick played by a notorious 

 trickster — the camera. However, it was the sight through the camera viewfinder that 

 revealed this resemblance, a sight not usually seen by the field entomologist because 

 the combination of focal length of the macro-lens and extension tubes produces an 

 image on an insect-to-insect scale. Even armed with a hand lens, the perspective and 

 depth of field of this image is not usually available to the human eye. 



During its five larval instars, the tortoise beetle larva, in this case Cassida 

 viridis L., carries about its previous larval skins, ornamented with its own droppings, 

 in the form of a 'parasol' which it waves over its back to deter any would-be 

 predator, or which camouflages the larva by resembling a bird dropping or other 

 rubbish. The particular structure which allows the larva to do this is a long 

 bifurcate prong called the caudal furca, caudal process, anal fork, or even 'feces fork' 

 (Gressitt, 1952). By the time it pupates, the accumulated exuviae and frass may 



Fig. 1. The fifth instar larva of Cassida viridis waves its 'parasol* of accumulated shed skins 

 and frass over its back while continuing to eat the mint leaf. Photo: R. A. Jones. 



