BUG VS. BUG. 25 



of Los Angeles, where he collected a large number of the beetles, and 

 found that fully one third were parasitized. He found them in the 

 larval state in the beetles as early as May and as late as the middle of 

 October. The May brood pupate early in June and remain in this con- 

 dition about two weeks, when they change to the winged form. They 

 are numerous in July and August. 



Masicera paehytyli, Sk. (Fig. 15.) This is one of the Tachnid flies, 

 the whole of which family are parasitic on other insects. They are of 

 medium size generally, and 

 to a casual observer resemble 

 our common house flies. The 

 favorite food of the greater 

 part of the members of the 

 family are the caterpillars. 

 The female lays her eggs on 

 the soft bodies of the caterpil- 

 lars and the young grubs de- 

 vour their host, which never 

 attains its mature state. It *' 



is tO this family that the re- FIG ]5 Masicera pachytyH, Sk. parasite of 



duction of moths and butter- the locust, 



flies below the danger limit 



is due. The one of which we give an illustration in Fig. 15 is parasitic 

 on the locust, and unquestionably does much toward keeping this terrible 

 pest in check in Australia, where it is native. This is one of the intro- 

 duced species and has been established in our State. Mr. A. H. Bray 

 gives his observations on this insect, as follows : 



The grub, or larva, is found within the locust, where it appears to live upon the 

 adipose tissues of the victim, avoiding the vital parts with unfailing instinct. The 

 grub lives indifferently in the thoracic region or the abdomen of the locust, and 

 frequently three or four may be found in a single grasshopper. 



The grubs leave their victims when they are full grown, usually by means of an 

 opening which they eat in tb.e side of the locust at the point where the abdomen joins 

 the metathorax ; but they do not invariably make their exit from' the body of the 

 unwilling host at that particular place, as on one occasion I observed two grubs 

 escaping from a grasshopper at the same time one from between the first and 

 second abdominal segments, and the other from between the head and prothorax. As 

 soon as the grub makes its escape, the grasshopper, which has gradually grown more 

 and more feeble as the inclosed parasite has gained in size, dies. In several instances 

 I have observed that the grasshopper died before its enemy succeeded in making- 

 its escape ; and in one case a larva was seen vainly struggling to free itself from 

 between the metathorax and the abdomen of a dead grasshopper, where it. was 

 firmly held by the contracting remains of its victim. The grub, which subsequently 

 died without extricating itself, succeeded in freeing more than half its body, but it 

 was firmly held by the tail. 



The Sypphidas, or syrphus flies (Figs. 16, 17, and 18), are another 

 large family of dipterous insects, many of which are beneficial to man. 



