254 



ENTOMOLOGY 



FIG. 247. 



upon 78 species of plants, in captivity upon 458 species (30 

 under stress of hunger, the rest freely), and refused only 19 

 species, most of which (such as larkspur and red pepper) 

 had poisonous or pungent juices, or were otherwise unsuit- 

 able as food. The migratory 

 locust is notoriously omniv- 

 orous, and perhaps eats even 

 more kinds of plants than the 

 gypsy moth. 



Galls. Most of the conspic- 

 uous plant outgrowths known 

 as " galls " are made by in- 

 sects, though many of the 

 smaller plant galls are made 

 by mites (Acarina) and a few 

 plant excrescences are clue to 

 nematode worms and to fungi. 

 Among insects,Cynipidse (Hy- 

 menoptera) are pre-eminent 



natural size; B, the gall-maker, twice as gall-makers and next tO 

 natural length. 



these, Cecidomyiidae (Diptera), 

 Aphididse and Psyllidae (Hemiptera) ; a few gall-insects occur 



FIG. 248. . 



B 



Holcaspis globulus. A, galls on oak, 



Galls of Holcaspis duricoria, on oak. Natural size. 



among Tenthredinidoe (Hymenoptera) and Trypeticlae (Dip- 

 tera), and one or two among Coleoptera and Lepidoptera. 

 Cynipidse affect the oaks (Figs. .247, 248) far more often 



