﻿176 SEVENTH ANNUAL REPORT 



The Locust Mite {Astoma gryllaria LeBaron, Fig. 36).— This, 

 though a smaller mite, is even a more efl5cient enemy than the pre- 

 ceding. Almost every one who has paid any attention to the locusts 

 [Fig. :;g ] must have noticed that they are often more or less cov- 

 ered, especially around the base of the wings, with small 

 red mites, seldom larger than the head of a pin. These 

 mites have but six legs which, though easily visible when 

 the animal first attaches itself, become more or less obso- 

 TiiE Locust ^^^® ^"^^ invisible as it swells and enlarges, though a 

 enlarged?^ ^'^' ^ careful examination will generally reveal them at the 

 anterior end of the body. The mite, therefore, more often presents to 

 the ordinary observer a bright red, swollen, ovoid body, so immova- 

 ble and firmly attached by its minute jaws, that those who are not 

 aware of its nature might easily be led into believing it a natural 

 growth or excrescence. In fact, it attacks the Locust precisely as the 

 diiferent wood-ticks attack man and the lower mammals. 



This mite belongs to the genus Astoma^ briefly characterized by 

 Latreille for a very similar mite {Astoma parasiticum) which affects 

 the common House-fly and several other insects. The specific name 

 locustarum was first proposed for it by B. D. Walsh,* but Dr. LeBaron 

 afterwards gave it the name of Atoma gTyllaria^\ in connection with 

 the following more detailed description : 



They are of an oblong, oval form, moderately convex and having an uneven sur- 

 face, produced by four shallow depressions on the upper side, the two larger near the 

 middle, and the others behind them. The body has also two slight constrictions, giving 

 it the appearance of being divided into three segments ; but the impressions are super- 

 ficial and only visible at the sides. The whole surface is finely striate, under the micros- 

 cope, the stride running in a waving transverse direction. The mouth-organs appear to 

 be reduced to their minimum of development. The only part visible, externallj% is a 

 minute papilla, on each side of which are two bristles, the inner of which is stouter, 

 tapering to an acute point, and curved inwards, or towards its fellow of the opposite 

 side. They difler from the majority of Acarides in having but six legs, and these, being 

 of but little use in so stationary a creature, are short and slender, projecting but little 

 beyond the outline of the body. They are G-jointed [in reality they are 5-jointed, the 

 middle joint much the shortest, and the terminal joint longest.— c. v. r ], garnished 

 with short stiff bristles, and terminate in two slender, curved hooks. The anterior and 

 middle legs are closely approximate and situated near the anterior extremity of th^ body; 

 the posterior are set a little nearer to each other, and a little in advance of the middle of 

 the body, being inserted at the posterior part of the anterior division or lobe. Pour 

 hairs project from the posterior extremity of the body. 



* Practical Entomologist , I, p. 126. 



t LeBaron's 2nd Ills. Ent. Rep. , 1872, p. 150. The author eniploy.s the temi Atoma, which, though 

 first so employcii by Latreille, is corrected to Astoma in his " Genera CriLStaceorum et Insectorum," I, 

 p. 102, (1800). 



