900 



Ri'RAT. SnicKiT. Leaflet 



Find some of the chrysalids. How are they attached to the leaf or 

 board? Deseribe their color and shape. Draw one of the chrysalids. 

 Watch one of them and see how the butterfly gets out of the case. 



How many wings has the butterfly? What is the ground color of the 

 wings above and below, and what and where are the markings? 



How many antennas has the butterfly? What is the shape and length 

 of each one ? Draw one of the antennae. Find the tiny watch spring on 

 the underside of the head. Uncoil it by passing a pin through the center 

 of the coil and straighten it out. How long is it? This tube constitutes 

 the mouth parts of the butterfly and it forms a sucking tube. With it, 

 the butterfly can suck up nectar from flowers. 



THE CABBAGE LOUSE AND OTHER APHIDS 



(Sucking insects) 



Glenn W. Herrick 



The cabbage aphis, commonly known as the " cabbage louse," came to 

 us from Europe. It was probably brought across the sea on cabbages 



imported for food. Now it is widely dis- 

 tributed all over the United States and is a 

 most serious pest on cabbages. Moreover, 

 it also feeds on turnips, cauliflower, brussels 

 sprouts, kohl-rabi, and other plants of the 

 mustard family. 



The life history. — If, late in the fall, we 

 were to examine carefully leaves of cabbages 

 that had been infested with this aphis, we 

 should almost surely find some of the dark 

 brown eggs of this little pest (Fig. i). Some- 

 times the eggs are laid in great numbers on 

 leaves, both on the upper and under sides. 

 In the fall of 19 lo we found as many as 342 

 on the underside of a single cabbage leaf. 

 The eggs seem to have a thick, heavy covering and they remain on the 

 old cabbage leaves throughout the winter, exposed to all the vicissitudes 

 of a winter season. In the spring the eggs hatch and the young lice 

 find a living for a time, at least, by sucking the juices from the tender 

 leaves of the sprouts sent out by the old stump (Fig. 2). In about two 

 weeks another generation of aphids is borne alive by the mother aphids 

 and in the course of two more weeks a third generation appears. This 

 rate of increase continues during the whole summer season; for genera- 

 tion after generation is produced as long as the food supply lasts and 



Fig. I. — Eggs of cabbage aphis 



