SCALE INSECTS OF IMPORTANCE 333 



White scale insect of the ivy 



Aspidiotus hederae Vallot 



PLATE 7 



This species is rather common in greenhouses in the state, and not in- 

 frequently it causes considerable damage, specially to ivy, its favorite 

 food plant. The ivy is not always killed, but the white scales on the 

 dark green leaves render it unsalable. Large quantities of this foliage 

 plant have been rendered worthless in this manner. 



Description. Infested plants may be recognized by the white, irreg- 

 ular patches of scale insects. An examination of one of these under a 

 lens will show it to be composed of a number of yellowish- white, circular 

 scales, each with a deeper yellow cast skin, or exuviae, a little to one side 

 of the center. The appearance of an infested spray of ivy is well shown 

 in figure 7. The large, yellowish-white scales are usually surrounded by 

 a number of small white ones. Such a group is represented much en- 

 larged in figure 6, and a full-grown female scale, which is about -j^ mch 

 in diameter, more enlarged in figure 4, while a young white scale is shown 

 very greatly enlarged in figure 3. Some of the yellowish, active young 

 can usually be found on an infested leaf. One is shown much enlarged 

 in figure 2. The removal of an adult scale may uncover a yellowish 

 female, represented in figure i, or there may be found only her shriveled 

 remains, shown greatly magnified in figure 5, and possibly a few very 

 minute yellowish eggs and one or two active young (fig. 8). 



Life history. The conditions in the greenhouse usually permit this 

 insect to breed continuously, so that there is no demarcation of broods. 

 Adult females, half-grown individuals and crawling young can usually 

 be found at almost any time. This insect lives outdoors in the southern 

 states, and, under these conditions. Prof. Comstock is of the opinion that 

 there are at least two generations annually. He bred adult males in 

 April from, specimens received both from California and Florida, but I 

 have been unable to find a sign of this sex on a badly infested ivy plant 

 kept under observation for some months. This species is apparently both 

 oviparous and ovoviviparous. I have observed eggs and living young 

 besides empty egg shells under female scales, and Mr Coquillett states 

 that he has witnessed the birth of living young. 



Distribution. This is a well-known European species which has a 

 wide distribution, having been recorded from such distant places as 

 Australia, Chile and Cuba. It has attained a general distribution in the 



