PUTNAM ON rULVINAKIA IKNTJMEEABILIS. 305 



ment ; fig. 25e represents the same from below. It w ill be noticed from 

 the last fi<?ure that there is still a considerable sp ice intervening between 

 the lobes of the seventh segment which eventnally meet on the median 

 line and form the so-called "anal fissure." 



The internal organs of the larva, and in fact the external as well, are 

 exceedingl}'^ similar to tlie adult female only more simple. The malpigh- 

 ian vessels/tracheae, stomach, and cephalic ganglion are well developed 

 and quite prominent, especially the two first named. In the body cavity 

 of the larva there usually remains a more or less considerable number of 

 yolk globules at birth, which serve as nutriment during the first few 

 days of its life. 



Habits. As soon as born the larvae begin to walk about quite ac- 

 tively and if not prevented proceed very soon to the leaves where they 

 settle down along the veins, mostly on the under side, (fig. 36) but a fair 

 proportion also on the upper surface. As the first hatched seem usually 

 to settle on the under side it is probable that they do not proceed to the 

 upper side until the desirable places on the under side are mainly occu- 

 pied. On the underside tiiey settle along the sides of the veins, with the 

 heads either up or down, rarely crosswise, making two rows along each 

 of the principal veins. On the upper side they settle directly over the 

 vein making but one row to eacli vein. As soon as they settle down 

 they thrust forth their slender setae, withdrawing tiiem from the loop in 

 the abdomen. The incision into the leaf is, I think, most probably made 

 by the ends of the setse themselves, worked by the muscles contained 

 within the head. Tiie object in going to the leaf is to find a soft place 

 in which to insert their tender beaks. On box-elder trees tlie larvae fre- 

 'quently settle on the younger shoots as well as on the leaves. 



They instinctively move towards the liglit and always upward. I have 

 frequently had them swarming on my table for days at a time, having 

 hatched from egg-nests brought in for examination, and they invariably 

 gather on the side nearest the window, and though they mount to the 

 top of the highest objects on the table, I have as yet never seen them 

 crawl over the edge and down the sides,— they die of starvation first. 

 When deprived of their natural food in this way they live for several 

 days without other food than the yolk globules which remain within the 

 body cavity at birth. During this period they increase r;ipidly in size 

 notwitlistanding their want of food. After being starved a few days 

 they become very transparent. 



When settled on the leaf the antennae and limbs are always arranged 

 in the positions substantially as shown in fig. 26, — the antennse are di- . 

 rected backward and outward, tlie anterior legs have the femur directed 

 outwards and slightly forwards, while the remainder of the leg is di- 

 rected forwards and inwards, nearly at right angles with the femur and 

 parallel with the antennae ; the middle and posterior legs are directed 

 backwards and inwards. iSoon after settling down, the anal filaments fall 

 off or otherwise disappear, while their conical bases remain and form a pair 

 of valves covering the anus. A thin layer of a waxy secretion begins to 

 form on the dorsal surface soon after the larva settles on the leaves. 



