April iSSS.J 



PSYCHE. 



41 



NOTES ON CROESUS Z ^ 77 7L47?5^6", NORTON, AND DESCRIP- 

 TION OF THE LARVA. 



BY JOHN GEORGE JACK, JAMAICA PLAIN, MASS. 



In the latter part of August, iSS6, I 

 collected a number of sawfly larvae, 

 found feeding upon the foliage oi Be tu- 

 la alba and B. papyrij'era, in this 

 vicinity. These larvae were nearly 

 fully grown and during the first week 

 in September they all entered some 

 loose soil and debris and made brown- 

 ish, oblong cocoons about I3 mm. long, 

 and 6 mm. in diameter. These w^ere 

 kept out of doors in a tin box, all winter, 

 and some of the peifect insects emerged 

 II May, 1887. 



On 14 June I found larvae in almost 

 all stages of growth, feeding upon birch 

 trees in the iVrnold Arboretum and 

 other places in the vicinity of Boston. 

 There were larvae nearly fully grown, 

 while others were just hatched, and 

 portions of the egg-shells remained, 

 arranged along the principal veins of 

 the leaf. About 18 June many of the 

 large larvae entered the soil to pupate, 

 and they emerged as perfect insects 

 15-20. Aug. Fresh specimens continued 

 to appear from pupae for about two 

 weeks after the last date. 



Larvae were found in all stages of 

 growth on 5 September. Most of these 

 had gone to tlie ground to pupate by 

 I October. Very few were found after 

 that date. 



The following is a rough description 

 of the mature lai-va. Head black, 

 shining. Body dull yellowish green, 

 the last two segments being rather 

 lighter than the others and varying to 



yellowish, especially beneath, and at 

 the extremity of the ventral segment. 

 A broad stripe, free from spots, extends 

 along the dorsal surface, from the head 

 to the anal segment. On each seg- 

 ment, just above the line of spiracles, 

 there is a large, irregular, black spot on 

 each side of the body. On the anal 

 segment, however, they are generally 

 very indistinct. The spots are usually 

 connected together by a cloudy band 

 which is sometimes so dark as to seem 

 almost like an unbroken black stripe. 

 Above the tip of the anal segment there 

 is a large triangular or shield-shaped 

 spot. Below the line of spiracles, and 

 above the legs, there are several black 

 spots, somewhat irregular and confused 

 on the thoracic segments, but becoming 

 more regular and distinct on each suc- 

 ceeding abdominal segment, until, on 

 the last segment with prolegs, they 

 appear as two distinct oblong spots on 

 each side. On the eleventh segment 

 the spots are less distinct and often seem 

 reduced to one, and in the last two seg- 

 ments they are entirely wanting. The 

 ventral surface, between the legs, is 

 usually more or less black. The tibiae, 

 tarsi, claws, and basal portion of the 

 femora of the legs are dark brown on 

 the external side. The prolegs are pale 

 Yellowish green and without spots. 

 There are a few very short hairs on the 

 head, along the sides, on the ventral 

 segment around the anus, on the legs, 

 and several on each of the prolegs. 

 Length 20-35 mm. 



The voung are pale green and the 

 spots are quite pale, but become darker 

 and more distinct as the larvae increase 

 in size. The larvae feed together until 



