18 



Fig. 5. — Head of wheat i)artially de- 

 stroyed )3y Itioaoina minutum (drawn in 

 Division of Entomology). 



are, except in rare cases, entirely devoid 

 of wings, and migration is therefore out 

 of the question, except for short distances. 



oviposition of the spring form 

 (minutum). 



At the time that the minute, wingless 

 females that comprise this form appear 

 in spring the 3'oung wheat plants are only 

 starting to throw the stem upward, and 

 if one will take the trouble to cut one of 

 them directly through the center, longi- 

 tudinally, he will be able to observe the 

 embryo head not far above the surface 

 of the ground. Pushing its ovipositor 

 through the stem to the center, the mother 

 insect places her egg in the embryo head, 

 which is not only the most vital part of 

 the plant, so far as the f ruitf ulness thereof 

 is concerned, but where her offspring will 

 be in the midst of the most tender and 

 highly nutritious food possible. As a re- 

 sult of this the j^oung head is destroyed 

 and further growth of the stem prevented. 

 In some instances the young larva is itself 

 destroy ed before it has finished its destruc- 

 tion of the head, and a distorted wheat 

 head supported b}^ a dwarfed and weakly 

 stem is the consequence. One of these 

 partly destroyed heads is illustrated in 

 fig. 5. In most cases the stem ceases to 

 grow, withers up, and dies, though usu- 

 ally standing upright, at the height of from 

 1 to 6 inches, with the leaves drooping down 

 about the stem, both dead and discolored. 

 In feeding on the young head the larva 

 forms a cell-like cavity which, owing to 

 the size of the larva and pupa, sometimes 

 takes on a somewhat gall-like appearance, 

 not noticeable except when cut in two. It 

 would seem that the superior article of 

 food which nature provides for these lar- 

 vae might to some extent account for the 

 larger and more robust adults which 

 constitute the second or summer brood. 

 The larvie must develop quite rapidly, as, 



