NATURE OF INJURY
Both adults and larvae feed on lily plants and the injury they cause may be grouped under three types, as follows : ( 1 ) The adults eat shallow, crescent-shaped notches on the edges of the foliage (fig. i) — a feeding only slightly detrimental to the plants hut furnishing an indication of the presence of the insects; (2) the larvae feed in the under-ground parts of the stems and (3) in the bulbs, both types of injury being very serious in their effect. Some small larvae apparently feed on the surfaces of the stems without making any effort to burrow within (fig. 2). These, while still small, either reach the bulbs or succumb to natural influences. Others very distinctly eat their way through the outer stem wall, at or below the soil surface, or at times even a little above, and tunnel up and down within the pithy interior (fig. 3). The
stem often is completely severed by such feeding, and the bulb, failing to receive plant food which is necessary for development, practically
ceases growth.
The larvae frequently complete their development in their burrows, which are more or less filled with frass (fig. 4). The stem tissue seems to be preferred by the larvae to bulb tissue. In older plants, with correspondingly large stems, more larvae have been found attacking stems than bulbs. The more extensive injury noted on bulbs of smaller and younger plants is possibly clue to the failure of the smaller stems to furnish sufficient food for the larvae.
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