ENTOMOLOGICAL SOCIETY OF ONTARIO. 61 



eggs on their bodies. From these eggs in a short time hatch white maggots which feed 

 inside the bodies of their hosts until full grown, when they force their way out and, falling 

 to the ground, which they enter a short distance, they pupate, and change to flies either 

 the same autumn or the next spring. Prof. Riley describes graphically the operation 

 of egg-laying by one of these Tachina flies, and much the same thing was observed by 

 Mr. J. E. Richardson of Princeton, Ont., last July. Prof. Riley says : " The slow- 

 flying locusts are attacked while flying, and it is quite amusing* to watcb the frantic 



efforts which one of them haunted by a Tachina fly, will 



make to evade its enemy. The fly buzzes around waiting 



her opportunity, and, when the locust jumps or flief, darts 



at it and attempts to attach her egg under the wing or on 



the neck. The attempt frequently fails, but she perseveres 



until she usually accomplishes her object. With those locusts 



which fly readily, she has even greater difficulty ; but, though 



the locust tacks suddenly in all directions in its efforts to 



avoid her, she circles close around it and generally succeeds 



in accomplishing her purpose, either while the locust is yet 



on the wing, or, more often, just as it alights from a flight 



£• • or a hop." Locusts infested with these parasites are more 



languid than they otherwise would be ; yet they seldom die until their unwelcome guests 



leave them of their own accord. 



Probably the most efficient worker in keeping down the undue increase of grass- 

 hoppers is the Locust Mite (Trombidium locustarum, Riley), and it has been extremely 

 prevalent and very often observed during the past summer. As it is seen attached to 

 grasshoppers, generally at the base of the wings, it bears little resemblance to an insect 

 and few recognize it as such the first time they examine it. The bright red swollen 

 bag-like bodies are really the larval form of the Locust Mite, and are possessed of six 

 weak legs, as may be discovered by examining them closely. (See figs. 62 and 63, opp. page 

 64) The mouth parts are very poorly developed, and, when once the mites have attached 

 themselves to their host by means of their beak-like mouths, they remain unmoved, living 

 on its blood until full grown. By these little parasites vast numbers of locusts are de- 

 stroyed. When ready to assume the pupal condition, they detach themselves, and, falling 

 to the ground, crawl under some shelter to complete their transformations. Gradually 

 swelling and changing their form slightly, the mites pass through the pupal stage inside 

 the larval skin ; new legs, mouths and other organs, of a different nature to those possessed 

 by the larvaa, are formed under the old skin, and finally this latter bursts and releases a 

 creature very different from and much more active than the larval form. It has now eight 

 legs and is a true Trombidium. The perfect mites are very conspicuous and draw attention 

 by their velvety, bright scarlet bodies ; they are frequently spoken of as " Scarlet Spiders " 

 when sent in for identification. In this stage they are equally useful allies to the farmer 

 as in the larval form, for while they do not attack the full grown locusts, they seek out their 

 eggs in the ground and destroy large numbers of them. They pass the winter in the 

 mature form and are frequently seen crawling over the ground in spring. 



In May the female lays a mass of between 300 and 400 small, round, orange eggs in a 

 cavity an inch or two beneath the surface of the ground. The young, as stated above, 

 have six legs only and are at first exceedingly minute but very active. They crawl about 

 until they find a locust, to which they attach themselves, mo3tly at the base or along the 

 principal veins of the wings. Here they swell by degrees until their legs become almost 

 invisible, and this is the time they are most often noticed. There has been considerable 

 confusion as to what is the proper name of this mite. In the first place, it was not known, 

 until Prof Riley in 1877 worked out the life history of this species, that the bag-like 

 bodies with six legs only, which were so often found attached to locusts, and which were 

 classified under an entirely different genus, Atoma ( = Asloma) of Latreille, were merely the 

 immature condition of the little red mites with eight legs which were found devouring the 

 eggs of locusts in the ground, and when this fact was discovered there was still room for con- 



* The locust might well say here, " It's fun for you but death to me." 



