26 



8. Colorado potato beetle, or potato bug, Leptinotarsa 10- 

 lineata Say. 



This common pest is the most important insect enemy of 

 potatoes. The hemispherical beetles are yellowish in color, 

 with ten longitudinal black lines on the wing covers. From 

 the eggs deposited on the under side of potato foliage emerge 

 reddish, soft-bodied larvse, or "slugs," which feed ravenously 

 upon the foliage. In four to five weeks these larvae attain full 

 growth and enter the earth to pupate. They remain in this 

 stage about two weeks and then transform to adult beetles. 

 There are two generations annually in Massachusetts. 



Control. — The bugs are readily killed by the use of ar- 

 senicals, such as arsenate of lead (see page 4). The vines 

 should be sprayed when they are a few inches high, and the 

 spraying repeated once or twice at intervals of ten days to two 

 weeks, or as often as necessity requires. 



9. Three-lined leaf beetle, Lema S-Uneaia Oliv. 



This somewhat common potato pest is closely related to the 

 Colorado potato beetle, but differs in appearance. The beetles 

 are about one-fourth of an inch long, yellow in color, with 

 three black stripes on the wang covers, and resemble some- 

 what the striped cucumber beetle. The orange-colored eggs 

 are usually laid on the under side of the leaves. The larvae 

 of this insect are dirty yellow in color, which readily distin- 

 guishes them from the reddish larvEe of the Colorado beetle. 



Control. — When present these insects may be controlled 

 by the remedies suggested for the Colorado potato beetle. 



10. Tomato horn worms, Phlegethonihis spp. 



These large green caterpillars are frequently found feeding 

 on the foliage of tomatoes and tobacco. When full grown the 

 caterpillars are ^rom 3 to 4 inches long, dark green in color, 

 and have oblique V-shaped white lines on each side. The 

 tip of the body bears a long, sharp, curved horn, which dis- 

 tinguishes this insect. 



Control. — When not very numerous they may be readily 

 controlled by hand picking. A single application of arsenate 

 of lead, either as a spray or dust, effectively destroys them (see 

 page 4). 



