THE HOUSE FLY 9 



attacks some food material and gorges herself. Then after 

 mating she, in a few days' time, seeks out the manure heap, 



FIG. 4. 



THE FULL-GROWN LARVA OR GRUB OF A HOUSE FLY. 

 (Enlarged.) 



the garbage box, a pile of decaying leaves, or any form of 

 filth which might be in the neighbourhood, for her sense 



FIG. 5. 



THE PUPA OR CHRYSALIS OF A HOUSE FLY, 

 showing back and side view (enlarged). 

 Within a week after the grub becomes a pupa 

 or chrysalis, a full-grown fly emerges. 

 (From " The House Fly," by L. O. Howard. Published by 

 Mr. John Murray, Albemarle Street, l^ondon.) 



of smell is extremely acute. Laying say 150 eggs, she 

 departs. Supposing these eggs all hatch and eventually 



