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Animalia >Arthropoda >Insecta >Lepidoptera >Gracillariidae >Cuphodes >

Many insects feed on plant leaves. For each species of plants, there are 1-2 insect species that eat only the contents of leaves. Larvae of lepidopteran Cuphodes diospyrosellus feed only on the fresh (mesophyll) of persimmon leaves, leaving both upper and lower epidermis intact. This moth does not cause much damage to persimmon trees because of parasitic wasps of the family Eulophidae.
Cuphodes diospyrosellus is known to construct a peculiar-looking cocoon during pupation. The cocoon is elliptical. The shape does not differ from those of other moths in Gracillariiformes. But larvae put a straight line of their fecal pellets on the egg surface. How could the larvae accomplish this? I had no idea until I saw it.
A late stage larva secretes a string of silk from its mouth. It brings the left and right sides of a leaf closer and makes a web in between. Gradually, it makes the web thicker into a cocoon. It defecates once in 7-10 minutes. As soon as it defecates, the larva grabs the fecal pellet with the mouth and pushes it outside of the cocoons through a gap in the cocoon web. It is easy at the beginning but gets harder and harder. As the cocoon web becomes thicker, it takes more time for the larva to make a gap in the web. The larva keeps turning around inside the cocoon so as to make the thickness of the cocoon even. Because a larva tends to defecate along the center line of the cocoon, the fecal pellets that were pushed outside of the cocoon end up with lying in a straight line. The fecal pellets at this stage differ from those in earlier larval stages. A fecal pellet of a pupating larva consists of small transparent bubbles and resembles a soccer ball, and is called a "Bable". Nothing is known about how Bables are produced within the digestive tract or about the role of Bables. Under SEM, horn-shaped crystals are visible within depressions of a Bable surface. Furthermore, something like virus particles less than 1 m long is seen over the crystal surface.

(Data No.momo050123cd01b)

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