INSECTS INFESTING THE SWEET POTATO 



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half a dozen species are common. They also affect morning- 

 glory; it is seldom, in fact, that the latter plants are free from 

 their attacks. The most common form of injury is manifested 

 by numerous more or less rounded holes eaten in the leaves, 

 and this, if traced to its source, will usually be found to be due 

 to the presence of the tortoise beetles. Some of these insects 

 are truly wonderful. The golden tortoise beetle, known as 

 "the gold bug," is one of the most beautiful creatures imaginable 

 when it is resting at ease or feeding in daylight. At this time 

 it has the appearance of a globule of burnished gold. If the 

 beetle is disturbed this golden color disappears, and it fades 

 also toward sundown and does not remain after death in dried 

 specimens. The larvae which produce these beetles are also 

 remarkable because of their singular habits. They are the 



Fig. 151.— Golden tortoise beetle. o, Larvae working on leaf; h< larva divested of 

 " pack "; c, pupa; rf, beetle, a, Natural size; b, c, d, enlarged. (After Riley) 



possessors of peculiar forked appendages which serve as recep- 

 tacles for their cast-off skins and for their excrement as it is 

 voided. When divested of the cast larval skins and excrement, 

 the larvae are seen to be fiat below, like the beetles, and convex 

 above, the margins projecting into peculiar-shaped spines. 

 These larvae are sometimes termed "pedlars," the fork with its 

 load being designated as the pack. Beetles, as well as larvae, 

 feed chiefly on the under surfaces when not exposed to direct 

 sunlight. Injury is mainly to young plants, the beetles making 

 their first appearance at about the time plants are reset. Soon 

 after appearing the females begin laying eggs, and in about 



