INSECT-ARCHITECTURE. 



181 



middle, next to the midrib, where it lies loosely in a little 

 cavity. While all this is going on her consort stands near 

 by, and she occasionally runs to him to receive his caresses, 

 again resuming her work. These rolls remain on the 

 A bushes sometimes for sev- 



eral days, but probably 

 drop by the time the larva 

 escapes from the egg; and 

 it seems probable that the 

 grub uses the roll for a 

 shelter until it matures 

 and is ready to enter on 

 its transformations to a 

 beetle. Another species 

 found on the oak does 

 not devote the whole leaf 

 to a single roll, for three 



FIG. 230. A, willow-leaves rolled by a caterpillar; B, willow-leaves rolled, seen 



in section. 



or four small rolls may be found on one leaf. 



The gall-makers are not the species of Cynips alone, but 

 also certain gnats and Aphides, including the Phylloxera, 

 which inhabit shelters, due to the morbid growth and mul- 

 tiplication of cells on the leaves and twigs, or roots, as the 



