306 EEPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



egg-mass of our Eocky Mountain locust, every egg of which contained 

 a Chalcid pupa. These pupse were too dry to permit of rearing the 



imago, but they were probably of the same 

 species as that reared by Mr. Scudder. It is 

 a black, deeply pitted fly (Fig. 38, a), about 

 5mm long, belonging to the subfamily Eury- 

 tomides. It does not fully correspond with 

 any of the genera defined by Westwood, 

 Walker, or Snellen Yan Yollenhoven. We 

 hesitate to found a new genus on a single 

 Fig. 38.— caloptenobia ovivora.— scx, but in Order to christen the insect, we 



a, female; b, her antenna. (After , . . -,•,.-, r, • - 



Eiiey.) subjoiu a brict definition : 



Caloptenobia, nov. gen. — $ , body elongate; strongly rugoso-punctate. Head as 

 broad as thorax; ocelli barely distinguishable, widely apart; antennae 12-jointed (scape 

 -f- 11), the scape nearly as long as the flagellum, whirh is curved, slightly clavate, with 

 joints 3, 4, 5, shortest, the others subequal, the terminal one faintly divided. Thorax 

 elongate; collare narrow; prsescutum large and swollen; scutellum small and rounded 

 behind ; metanotum concave behind, with the sides dilated and forming almost a qua- 

 drangle. Pedicil short and stout. Abdomen flattened, fusiform, 6-jointed ; joint 2 exca- 

 vated anteriorly, joint 3 as long as 1 and 2 together, the terminal joint very small and 

 indistinctly separated. Wings not reaching to tip of abdomen when closed ; hind pair 

 with a fringe of sparse cilia on inner border. ^ unknown. 



C. ovivora, n. sp. — $ , color pitchy black, with sparse gray pubescence. Legs, scape, 

 and basal joint of flagellum honey-yejlow. Wings hyaline. Head and thorax broadly 

 and confluently rugoso-punctate. Abdomen longitudinally striate. Length 5™™. 



Four specimens from eggs of (JEdipoda Carolina. 



Finally, the Locust Mite, which we shall now consider, is, in the mature 

 state, one of the most effective destroyers of the locust eggs. 



ANIMALS THAT PREY UPON THE LOCUST AFTER IT IS BORN. 



Red mites, — There are at least two species of red mites, and prob- 

 ably more, that attack the Eocky Mountain locust, the most common 

 of which is — 



The Locust Mite ( Tromhidium locustarnm Riley). — Orie of the most 

 interesting as well as one of the most important of our locust enemies 

 is what we may popularly call the " Locust mite." It forms a true link 

 between those articulates which prey on the eggs and those whicli prey 

 on the locusts, since it combines both traits. Referred to in previous 

 writings under the name of the Silky mite, its natural history was first 

 fully made out by Mr. Eiley during the past summer. It differs so 

 much in infancy and maturity that it has been referred to distinct 

 genera, and was always known under two different names. During 

 either period it proves a bitter enemy to the locust. In the mature form 

 it lives in the ground, feeding upon all sorts of soft animal and decom- 

 posing vegetable matter. When the locust fills the ground with its eggs 

 this mite flourishes upon the abundance of food which these afford, 

 sometimes teeming to such an extent as to give the ground a scarlet 

 hue. How numerous and how beneficial to man this mite may be as a 

 destroyer both of the locust and its eggs is well illustrated by the state- 

 ments of correspondents in the appendices (App. 18) where it is so fre- 



