904 



Rural School Leaflet 



many plant lice before it becomes full-grown. A syrphus fly is shown 

 in Fig. 4. It is somewhat larger than a house fly and has yellowish 

 bands running across the abdomen. 



Plant lice are also subject to the attacks of several small, blackish, 

 four-winged, fly-Hke insects (Fig. 6) that sting the aphids by laying their 

 eggs inside the bodies of the lice. The eggs hatch and the tiny parasite 

 lives inside of the body of the aphid, finally causing the latter's death. 

 When the parasite becomes grown and is ready to emerge from the body 

 of the aphid, it cuts a neat round door in the back of the louse and crawls 

 out, ready in a short time to attack another victim. In Fig. 7 are shown 



Fig. 6. — Two parasites of the cabbage aphis 



aphids that have been attacked by one of these parasites and have the 

 tiny doors cut in the top of their bodies. 



LESSON FOR THE PUPILS 



Method. — Plant lice are very common in summer on many plants, 

 usually on cabbages, roses, apple trees, and the like. Young cabbage 

 plants will grow well in a window of the schoolroom and the lice may be 

 transferred to the plants and watched day by day. Their movements 

 and habits will prove very interesting. The cabbage lice are covered 

 with a whitish powdery material and do not seem to secrete much honey- 

 dew. If the secretion of honeydew is to be observed, plant lice from 

 elm or maple trees, or from other plants, should be collected. 



Observations for the pupils. — 



1. How large is a plant louse? What is its color and shape? How 

 many legs has it ? 



2. Has it any antennae, or " feelers"? How many antennas has it? 



