170 TRANSACTIONS OF THE 



season may this parasite be seen, like little red bladders, attached to 

 the Avings, legs, or antennre, often a dozen upon one individual. This 

 is the minute six-legged form, once called Astona. When full of 

 blood the legs can scarcely be detected near the mouth or beak, which 

 is the only point of attachment to the locust. AVhen a locust is 

 attacked with several of these mites it becomes pale and weak, and is 

 seen vainly trying to scratch off the vermin, which for this reason 

 are found most numerous near the wings. When satiated, these 

 blood-suckers loose their hold, drop to earth, crawl clumsily away to 

 the shelter of loose earth or stones, and then undergo a very singular 

 transformation, coming out the beautiful, eight-legged, red silky 

 mite, named by Professor Riley Trombidimn locustarnm, first described. 

 In the adult state this insect preys upon the locust eggs, creeping 

 down into the' nests and voraciously eating their contents. In the 

 interior great plains they have been noted so thick on the ground 

 when hunting for eggs of the spretus as to give the soila crimson 

 color, and they have been credited with the total destruction of the 

 egg crop in many places. 



THE TACHINA FLY. 



This watchful and industrious enemy resembles the common 

 house fl}^, but is usually larger, gray-colored, with the tip of the 

 abdomen yellow. It does not prey upon the locust for its own sake, 

 but for its progenj^ With the most persistent and skillful move- 

 ments the Tachina follows the locusts, sometimes in svv^arms, and at 

 every opportunity darts upon them and seeks to deposit an egg upon 

 the neck or under the wings, where it cannot be removed. One who 

 has noticed the conduct of a horse when beset by a bot fly, how he 

 strikes, or runs about almost frantic, as though in great pain, through 

 instinctive fear of bots, can imagine the desperate efforts of a locust 

 when haunted by a Tachvua. But the latter always succeeds. The 

 egg soon hatches, the maggot eats its way into the softer parts of the 

 locust, riots upon the fatty portions, leaving the vital parts unharmed 

 until it becomes a large, oval, white object, distending the locust to 

 the utmost capacitj^ of the abdomen, and bringing it into a state of 

 nearly inactivity. In due time its host, while perhaps trying to 

 deposit eggs, falls on her side and dies; a hole in her underside tells 

 where the fostered maggot has gnawed out and escaped into the 

 ground to undergo its transformation. 



THE CHALCID FLY. 



Another enemy greatly feared by the locust is a minute, ant-resem- 

 bling fly of the Chalcis group. It has monstrous enlargements of the 

 hind legs just above the foot; yellow, lenticular, and prominent, they 

 resemble pollen baskets of a bee. This little swift-flying insect pur- 

 sues the locust, and hovering over its head, attempts, by a quick thrust 

 of its ovipositor, to place an egg upon its head or in the sutures of its 

 neck, meanwhile dexterously dodging the blows aimed at it by the 

 frantic locust. My close observing brother, B. F. Lemmon, and myself, 

 watched it particularly, when attacking female locusts ovipositing. 

 Frequently the locust would duck and dodge about, strike with her 

 hind feet, or hasten away to another spot, but becoming wearied or 

 perhaps more concerned in her work of providing for the continiia- 



