ROOT CROPS. 51 



The Potato Frog Fly {Eupteryx solani, Mg. 21) 

 is a small green insect, measuring only one-sixth of an 

 inch in length. It is provided with four wings, two short 

 antennsB, placed between a pair of brown eyes. There 

 are six legs. The posterior pair are very long, which 

 assist the insect in performing most extraordinary leaps, 

 — hence the name of " frog fly." 



The eggs (Fig. 21 B) are white, and about one-twentieth 

 of an inch in length. The larva and pupa are both some- 

 what like the perfect insect in shape, provided with six 

 legs, two antennae (long), and a sucker. They are wing- 

 less. Eupteryx solani (in all three stages) lives upon the 

 juices of the leaves and stems of the potato plant, which 

 it pierces by means'of its sucker. 



Cure. — A dressing of lime, sulphur, or soot. 



The Potato Disease F\ingus {Peronospora infes- 

 tans, Fig. 22). The life-history of this fungus has been 

 thoroughly investigated by Rayer, Montague, Berkeley, 

 De Bary, Smith, and others ; but to Mr. "W. G. Smith, 

 F.L.S. (who discovered the reproductive organs and the 

 oospores), is the honour of having made a thorough study 

 of this fungus. 



The potato disease (the so-called "curl") makes its 

 appearance in July or August, especially in moist warm 

 weather ; and commences its attack by settling upon the 

 leaves of the host-plant. The leaves become spotted 

 (blackish), and have a tendency to curl up. After piercing 

 into the interior of the leaves, the fungus spreads its 

 mycelium through the tissues of the stems and tubers of 

 the potato plants. Its growth is very rapid, and it pro- 

 duces in the host complete decomposition of the parts in 

 contact with it. 



If a transverse section of a diseased potato leaf (Fig. 



