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THE EGGS AND LARVAE OF CRYPTOCEPHALUS QUADRUPLEX NEWMAN AND C. VENUSTUS FABRICIUS, WITH A KEY TO THE KNOWN IMMATURE STAGES OF THE NEARCTIC GENERA OF CRYPTOCEPHALINE LEAF BEETLES (COLEOPTERA: CHRYSOMELIDAE)

Published online by Cambridge University Press:  31 May 2012

Laurent LeSage
Laurent LeSage
Affiliation:
Agriculture Canada, Biosysternatics Research Institute Ottawa, Ontario, Canada K1A 0C6
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Abstract

The eggs and larvae of Cryptocephalus quadruplex Newman and C. venustus Fabricius are described and illustrated. Both species very likely overwinter in the larval stage. The adults emerge from the last week of May to mid-June. Before mating they feed on plants for about a week. The oviposition period is quite extended and lasts from mid-June to the end of July. The eggs are laid singly in the leaf litter. The hatching period was 10–15 days in the laboratory. The larvae develop through 5 instars and feed exclusively on dead or decaying leaves of various plants. By the end of September most of them have grown to the 4th instar, some to the 5th. At this moment they stop feeding and move deeper in the leaf litter for overwintering. The 1st instar is easily recognized by the presence of the egg bursters on meso- and metathorax, the large flattened-papillate setae of the head capsule, and the presence of 2 pairs of spiniform setae on tibiae. In the following instars the size varies as well as the number of spiniform setae on the tibiae and the number of secondary clubbed setae on the pronotum.

Résumé

L’auteur décrit les oeufs et les larves de Cryptocephalus quadruplex Newman et de C. venustus Fabricius. Les 2 espèces hivernent vraisemblablement à l’état larvaire. Les imagos émergent de la dernière semaine de mai à la mi-juin. Avant de s’accoupler, ils s’alimentent environ 1 semaine. La période de ponte est assez longue et dure de la mi-juin à la fin de juillet. Les oeufs sont pondus isolément dans la litière. La période d’éclosion varie de 10–15 jours en laboratoire. Les larves passent par 5 stades de développement et se nourrissent exclusivement de feuilles mortes ou en décomposition. Vers la fin septembre la plupart ont atteint le 4ième stade et quelques-unes le 5ième. A ce moment, elles cessent de s’alimenter et s’enfoncent dans la litière pour hiverner. Les larves de premier stade se reconnaissent aisément par la présence d’ovirupteurs sur le méso- et le métathorax, de grosses soies aplaties-papilleuses sur la tête et de 2 paires de soies spiniformes sur les tibias. Chez les stades suivants la taille varie ainsi que le nombre de soies spiniformes sur les tibias et le nombre de soies secondaires en massue sur le pronotum.

Type
Articles
Information
The Canadian Entomologist , Volume 118 , Issue 2 , February 1986 , pp. 97 - 111
Copyright
Copyright © Entomological Society of Canada 1986

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References

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