58 



Flu. f)0.— llciul of plimt- 

 louse, showing buck- 

 ing bi'ivk— imic'li cii- 

 largod (original. Divi- 

 sion of Entomology). 



PLANT-LICE. 



Several forms of j^lant-lico ati'ect the loaves of sugar beet, l)ut as far 

 as at present known do not iniliet extensive injnrv. Among the plant- 

 liee, however, are some few forms Avhich have tlie hal)it of feeding on 

 the roots, Ix'ing known as root-liee, and these arc of the greatest 

 inipoi'tanc(». when atmospheric conditions conduce 

 to tiicir (h»\'cloi)mcnt or the i)iants arc iir.st injured 

 through other causes. 



THE MELON PLANT-LOTTSE. 



( Aj>h t.s (joxxi/jdl. (.i ]o\ . ) 



The melon plant-louse or, as it is more commonly 

 known, the melon louse, is perhaps the commonest 

 species found on l)eets, and is the best known as 

 well as most destructive of all insects of this class. 

 Fortunately for the beet grower it does not favor 

 this crop, and is usually found only in moderate 

 numbers on beets when othei- plants are available. 

 The writc^" has sihmi a considerable number of this species on beet 

 leaves working in their usual manner by pumping up the juices 

 through their beaks (tig. r)(i), l)ut although tlie plants were carefully 

 watched the operations of the plant-lice did not seem to hinder the 

 growth of the plants in any degree. Neverth(dess, this louse is capa- 

 ble of serious damage, more especially in the cn'ent of exh:nistion of 

 favorite host i)lants, like melons and 

 other cucurbits, which would drive it 

 to beets if these were most availal)le. 

 The prinei})al forms of this insect are 

 illustrated in figure 57. 



The melon louse is i)ro])al)ly ol' 

 American origin and perluips tropical, /U^\ 

 since it prefers plants of a trapiciij \^^j ] 

 nature, has a very wide distribution ' -^ 



in North and South America and the 

 West Indies, and has been observed in 

 Australia. It is therefore apt to be 

 present in most lields of sugar beet, 

 but its occurrence there can usually be 



traced to other plants on which it develops more freely, some of which 

 have already been mentioned. Among others of the favorite host 

 plants are cotton, okra, purslane, strawberry, and orange and other 

 citrus trees. Attack begins in early spring and may last until winter, 

 according to season, climate, and other cii-ciuustances. 



Natural enemlex. — As an illustration of an insect ])est lu>l(i in abey- 



Fi(i. bl.— Aphis yosDi/pii: a, winged female; 

 tut, oTilargcd antenna of same; ah, dark 

 fonialo, side view; h, young nymph or 

 larva; c, last stage (f nympli; (?, wingles.s 

 female— all greatly enlarged (original, 

 Division of Entomology). 



