INSECTS. ■ 219 



the potato. The smaller one, which is cream color with three 

 black stripes on the wing covers and looks very much like 

 the common striped cucumber beetle, but is larger and stouter, 

 is the species which has been common in New England for 

 many years but is not usually abundant enougli to destroy 

 the crop. The larger, short, oval species with ten black lines 

 placed longitudinally on the wing covers, is the western, or 

 Colorado potato beetle, which for a few years past has almost 

 destroyed the potato crop at the west. It is rapidly spreading 

 eastward and there is no telling how soon it may be among 

 us. It is important to distinguish between these two beetles? 

 for it has several times been stated that the western species 

 was already found in the eastern states, the observers mistak- 

 ing the common small species for the far more destructive 

 species of the west. 



Dr. Riggs. — I have noticed on my plants, and on the tender 

 shoots of my apple trees, this green plant louse in quite large 

 numbers; and I have noticed small, brown-colored ants, run- 

 *ning around among these lice. Are they destroying the lice, 

 or do they live on the exudations or secretions of the body of 

 the louse ? 



Mr. Smith. — If you notice these lice, and especially if you 

 examine them with a magnifying glass, you will see that they 

 exude, from two little tubes at the posterior part of the body, 

 a sweetish substance, which is sometimes called "honey dew." 

 This frequently drops on the leaves. The ants are very fond 

 of it, and climb up the trees or other plants and feed upon it- 

 The ants never eat the aphis, that I know of. 



Dr. Riggs. — I have seen it stated that the worm which feeds 

 on potatoes is the same kind that feeds on tobacco. 



Mr. Smith. I know that is a very common idea, but prob- 

 ably erroneous. At least there are two quite similar but dis 

 tinct species, one of which usually feeds upon the potato and 

 tomato vines, the other upon tobacco and also on the tomato. 

 The potato worm has the oblique stripes on the sides of the 

 body greenish yellow, and the feet and the horn upon the end 

 of the body black, while in the tobacco worm the oblique 

 stripes are white, and edged above with bluish and short trans- 



