Tuesday, January 13, 2009

Tortoiseshell Beetles
Tortoise beetles range between 9 and 12 mm (less than 0.5 inch) in length and resemble a tortoise because of the forward and sideways extensions of the body. In some western countries tortoise beetles are among the most brilliantly colored coleopterans and are used in making jewelry.
These insects easily attract the attention of nature lovers due to their brilliant and attractive metallic golden colors. The golden tortoise beetle is associated with sweet potato and related species such as morning glory, Ipomoea species. On this plant, the entire life cycle takes place. Eggs are laid in-groups and are cemented together in a paperlike egg capsule whose thin brown layers separate and camouflage them. The larvae, which hatches in four to six days burrows directly through the egg capsule and feed on the leaf epidermis. Larvae are broad and flattened and adorned with branched spines. Their thoracic legs are short and thick. The color of the larva is yellowish to gray. There are three larval instars. The larvae display the habit of carrying their cast skins and fecal material attached to spines arising from the posterior end of their body, a structure called an "anal fork." The anal fork is movable, and is usually used to hold the debris over the back of the body, forming a "shield" which deters predation. Larvae mature in 14-21 days. They are always in groups say 30 to 40 upto 100 on a single underside of the leaf. When the beetle emerges it is white in color then it changes its color gradually into orange and then finally metallic gold.
The adult beetles are distinctive in that the margins of the prothorax and elytra are expanded, largely concealing the head and appendages. The expanded margins are not pigmented, appearing nearly transparent. The beetles vary slightly in color but invariably are orange colored, often golden metallic, and are sometimes called "goldbugs." There are some tiny metallic green varieties also in our forests.
Yuwaraj Gurjar.

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