396 NATURAL HISTORY OF HAWAII. 



grass feeders, while two species feed exclusively on sedges. The genus Omiodes 

 have been extensively studied by economic entomologists, who find the cater- 

 pillars of the species are attacked by a number of parasites, some of which are 

 native, liut several of the most valuable have been introduced. The cane leaf- 

 roller and the palm leaf-roller are the two most injurious species. The para- 

 sites do much good, but at certain seasons, especially in winter, and in certain 

 localities the cateri>illars get the start of their enemies, and one or two broods 

 appear before parasites are abundant enough to check them. 



Sometimes as high as ninety per cent of the caterpillars are found to be 

 parasitized. One might ask, "Why are they not completely exterminated or, 

 at least, why do they continue to do so much damage!" The answer seems 

 to be that, although they have many enemies that prey upon them, they are 

 still prolific enough to overbalance their enemies. It is difficult to estimate 

 the damage they would do were they entirely free from their burden of 

 parasites. 



Cutworms. 



Cutworms of various species are a serious agricultural drawd^ack, as they 

 attack corn, tobacco, cotton, cabbage, wdieat and other useful plants, nipping 

 the young plants off at the surface of the ground before they have fairly started. 

 There are several species of these night maraudei's. but they all belong to a 

 family of owlet moths or Xoctuids (Xocfuidfp), one of the largest groups of 

 the order Lepidoptera. They feed at night in the larval stage and fly by night 

 in the adult stage, often being attracted by lights. The fact that their eyes 

 shine brighly in a dim light and that they are seldom seen in the daytime has 

 resulted in the populai' name for the adults, while the unfortunate haliit of the 

 larvjv has given them the unenviable name of cutworms. The species are 

 mostly small-sized, dull-colored moths. The most troublesome species in Ha- 

 waii are the widely-known and doubtless introduced black or corn cutworm ^^ 

 with the hind wings greenish; and a second si^eeies. a large native cutworm,'^*'' 

 with fuscous-colored hind wings, both being plentiful on corn and other field 

 crops. A third species known as the small native cutworm "'" is also common. 

 They are kept in check in Hawaii to some extent by their natural enemies, 

 which include both parasites and birds, but as there are two or three dozen 

 native species, the caterpillars of all of Avhich resend)le each other and have 

 similar habits, it is difficult to identify the spices that feeds on the various 

 crops and weeds, even when adult specimens are securetl. 



Army- Worms. 



The widel.v-known ai'iiiy-worm,"''^ with its cousins the grass army-worms, ^'^ 

 at times do much damage to grass and forage crops. They appear in great 

 numbers occasionally, and after destroying the vegetation in the field where 



^^Ar/rotis ypsilon ^" Ai/roHti criiiii/fra. ^~ Ar/rofis dixlorntri . •'''* Ifi'liniiliihi iniiinnictn. 



5i» Spodoptera mauritia and Spodoptera exiyua. 



