180 Bulletin 190. 



closelv attached to tlie undersides of the leaves in clusters of from 

 eight to twelve, often two to four of which niaj overlap, as shown 

 at e in figure 47. The q^^^i^ shell is finely reticulated, and is 

 apparently not easily penetrated by liquids as caterpillars were 

 reared from ec-f^s which had been soaked in water for two davs. 

 Observations indicate that the egg-stage lasts about twelve days. 



The full-grown caterpillar or larva is about three-fourths of an 

 inch long, and of a general translucent greenish-wliite color ; its 

 liead is of a dark straw color with darker mottlings, and there is a 

 small, conspicuous black spot in the center of each half of the 

 prothoracic shield. A narrow dark green stripe extends medially 

 along the back, bordered on each side by a much wider, light 

 greenish-white stripe ; there are five pairs of pro-legs, the last pair 

 projecting behind when the larva is at rest. The general character- 

 istics of the caterpillars are well shown in figure 49." 



The caterpillars are about twenty daj's in getting their growth 

 and shed their skins tlii-ee times or pass through four stages during 

 this period. Usually they move about but little, almost completely 

 devouring one leaf before going to another. AVhen touched, how- 

 ever, they are very active, wriggling quickly backward or forward. 



When full grown the caterpillar folds in a lobe of the leaf and 

 fastens it securely with silk, as shown at c of lower leaf in figure 47 ; 

 if the leaf is not lobed, the caterpillar will eat into it to loosen a 



* When fiist hatched, the hirvse are of a creamy- white color, but soon become 

 greenish from !h(; food eaten. The head is blackish and the black thoracic spots 

 more or less indistinct. They merely eat small holes through the lower skin of 

 the leaf during this stage which lasts live days. After the first moulting of their 

 skin, the larvae assume most of the color characteristics of the full-grown larva, 

 but are lighter iii geiiv.-ral color. Tlie}'^ are active, moving freely from place to 

 place on the plant searching for suitable feeding places ; they spend four days 

 in tliis stage. The next or third stage is passed in four days also, and during 

 this time the larva feeds voraciously, increases much in size, and looks much like 

 the mature larva. At the next moult the larva3 enter the fourth and last cater- 

 j)illar stage when they are also ravenous eaters but move about less than in the 

 third stage. The fourth stage lasts eight days. 



Dyar's method of measuring the diameter of the head in each stage was found 

 to work fairly well. The average ratio was found to be 1.516, and the diameters 

 for each stage were .24 to .36 mm.; .45 to .54 mm.; .73 to .78 mm.; 1,01 to 

 1.17 mm. 



