1915] Sevcrin, Severin and Ilarfuny — Leaf -ovipositing Tachinidcr 133 



and believed that the mandibles of the host crack the egg-shell, 

 allowing the maggot to escape. It appears to us that Swezey's 

 explanation of the method of hatching of the egg is faulty in some 

 respects. If the jaws of the host were to exert too much jjressure 

 upon the egg-shell the maggot would be crushed. Again, by what 

 mechanism would those eggs hatch which were swallowed, but did 

 not first have the chorion cracked by the mandibles of the host? 



In order to obtain the eggs of the same species of tachinid (Choe- 

 togcrdia vionticola Bigot) with which Swezey worked, a careful 

 study of the egg-laying habits of this insect under natural condi- 

 tions was made in the Hawaiian Islands. The fly usually deposits 

 its eggs on different species of grasses and weeds. In observing 

 the behavior of the parasitic fly, one is at first inclined to believe 

 that the female searches for cutworms in the grass. The insect 

 often crawls down into the thick matting of grass and disappears. 

 Sooner or later it reappears, crawls up a blade of grass and stops 

 a moment to deposit an exceedingly minute, black egg. As the 

 tachinid crawls towards the tip of the blade of grass, the leaf bends, 

 and it then grasps another blade of grass, crawls down, stops a 

 moment to oviposit and again it may disappear in the thick mat- 

 ting of the grass. Occasionally the creature may rest to go through 

 cleaning movements or to lap up some food. Often Chseto- 

 gsedia takes short flights, only to resume egg deposition in a new 

 locality. When disturbed, it flies away with a loud buzz, so 

 quickly that the eye can hardly follow it. 



To obtain the eggs of this leaf-ovipositing tachinid, specimens 

 of Chcetogsedia were captured in the field and placed in a glass 

 jar provided with a cover. The bottom of the jar was covered 

 with moist filter paper on which was placed a wet sponge. The 

 cover was propped up with a toothpick to allow circulation of the 

 air and thus prevent the accumulation of moisture on the sides of 

 the jar. The food that was placed in the jar consisted of the pulp 

 of ripe bananas and sugar. Under these conditions the flies de- 

 posited hundreds and hundreds of eggs on the moist filter paper. 

 The pulp of the banana seemed to be especially attractive as a 

 medium for egg-laying, for the fruit was often blackened by hun- 

 dreds of tiny eggs. 



A number of experiments were performed to determine whether 

 the eggs of the leaf -ovipositing tachinid would hatch in the juices 



