I'lKlUNAK; IMKlilS Ol.KlIAl 'KA. 1199 



Kitoh gives ji slightly (lifVciciit ai-i-mml ( lu|i. ins. N. \'.^ xiii : 533.) : — 



Ali'Tlitlii]:;, it stands upon tlie edge of the lenf. iiiid h.-iiillnj; Its body downward it 

 lonolics tlie tip of the under surface of the leaf, plantln*; an e<rf< thereon, placing it 

 from an eifthth to a quarter of an incli '.inward from the ed-^e of tlie leaf. From one 

 to three eirsis, placed sli^htl.v apartjfrcini each other, are thus glued to the under siile 

 of the leaf, when it a'^ain tako-i wiii'.;:ind s -arches out another leaf such as it desires. 



CoiiptT sny.s tliiit tlx' cgjr'' !"■*■ i'l"i'.vs I;ii(l (in ilir upper si<lo of .a Icnf 

 and that lie liajs found as many as five on a leaf. .Mrs. Charlotte Taylor, 

 aceording to Riley, "has never found the eggs deposited in any place ex- 

 cept just where the leaf joins the cabbage stalk, down in the rim of the 

 mid vein." 



Food plants. Tiiis caterpillar feeds on various cultivated cruciferous 

 plants, smh as turnij) ( 15rassica rapa), cabbagt; (B. oleracea), radish 

 (Raphanus sativa), horseradish (Nasturtium armoracia) and mustard 

 (Sinapis). Mr. Lintner considers that it prefers turnip to calibage, for 

 he once obtained fifty eggs from a turnip bed and could find none on ad- 

 jacent cabbage plants of the same age, and this has been my experience. 

 Hoy. on the other hand, thinks it is found mostly on mustard. 13ut it 

 also occurs on some of our native plants, such as Arabis druniinondii 

 (Couper) and A. perfoliata (Fletcher), and Fitch says it occurs abundantly 

 on the water cress (Barbarea vulgaris). In Colorado I saw the female 

 lay an egg on Caltha Icptoscpala, one of the Ranunculaceae. 



Habits of the caterpillar. The escaping caterpillar eats its way 

 througii a hole just large enough for egress, in one side near the summit of 

 the egg, and then usually devours most of the remainder. Jlr. Lintner 

 watched one make its way out. 



For a half hour it was seen to be vi<;orousI_v plvinjr its blacl^-tipped mandibles on 

 the interior surface next the apex, before it cft'ected an opening. The opening made 

 with so much labor was rapidly enlarged by the larva eating a sufficieut portion of the 

 shell to permit its egress. Immediately upon having wholly withdrawn itself, it re- 

 sumed Its feeding upon the shell, nearly all of which it consumed. 



The first stage lasts but two or three days, and it takes it but about two 

 weeks or a little more to reach maturity, whether in the first brood or the 

 second. Fitch says (loc. cit.) : — 



It eats small, round holes through the leaf when it is young, larger and less regular 

 ones as it advances in size and approaches maturity. It feeds mostly by night and re- 

 mains at rest during the day, frequently standing in tlic groove made by the midvein 

 on the upper side of the cabbage and turnip leaves, with its head downward, toward 

 the base of the leaf. But if there is a fold in the margin or any other covert where 

 it will he more Irid from view, it conceals itself therein. It resorts to the same place 

 upon the leaf day after day, spinning and fastening to tlie surface an exceedingly flue 

 ■web of silken threads, to give it a more secure foothold. It moves about but little, 

 crawling very slowly, with its mouth to the surface on which it is crawling, placing 

 there a silken thread to aid it in clinging. It seldom quits the leaf on wliich it is 

 placed, if this is of sudlcient size to fully feed it. 



The early stages are more quickly passed than the later, and the larva 



