132 UNITED STATES NATIONAL MUSEUM BULLETIN 2 76 



and, of course, contained specks, male terminalia : The terminalia of 

 die A's and B's were similar in size and shape; those of the BS's were 

 essentially the same except for being slightly smaller, as were the moths. 

 FEMALE terminalia: The genital plate of the A's and B's usually was 

 almost entirely sclerotized (similar to fig. 95) ; the genital plate of the 

 BS's generally was less completely sclerotized (similar to fig. 102). The 

 ovipositor lobes of all three populations were basically the same. 

 LARVAE : All three populations show much variability in markings and 

 colors, and no consistent differences of any kind were found which will 

 positively separate them, although a higher proportion of the A's and 

 B's have the conspicuous Dl black spots (figs. 388 and 389) than do 

 the BS's which more often have the black addorsal areas more similar 

 to figures 385 or 387. 



Additional support for these differences can be obtained by comparing 

 collections 441, 441a, and 442. Collection 441 was made on clumps of 

 chokecherry growing in the open along the roadside. Nearly all of the 

 larvae were gone and the few that remained were wandering about on 

 the foliage so they could not be associated with any single tent or egg 

 mass. Tents were numerous and nine old egg masses were collected. 

 Later, after the existence of specks in the spumaline had been discovered, 

 these egg masses were examined. Four of them were found to contain 

 specks (referred to as 441a) and five of them did not contain specks 

 (referred to as 441). In addition, the color of the spumaline of the 441 a's 

 was grayish and all four egg masses had been laid near the base of the 

 main stem, while the color of the 441 's was tan-brown and all five egg 

 masses had been laid on twigs. This difference in oviposition site should 

 not be regarded as constant, since the oviposition site of other species 

 such as M. americanum is known to vary similarly, and in collections 

 such as 438 (with specks) and 448 (without specks) egg masses were 

 found on both twigs and large branches. Nevertheless, the normal 

 oviposition site of the A's is on small twigs, and if the B's are regarded 

 as being part of the A's, one would expect most of them to lay their 

 eggs on twigs when they oviposited on brush species. 



A check of the adult females which had been reared from the larvae 

 which were collected on chokecherry showed that all eight females 

 had no specks in their spumaline, indicating that all of them probably 

 had hatched from the 441 ^gg masses which contained no specks and 

 were laid on the twigs. Any larvae which may have hatched from the 

 441a egg masses containing specks either had pupated already or had 

 died already when the collection was made. Most likely they had 

 already pupated. Colonies on aspen growing nearby (Coll. 442) 

 contained larvae in the next to last and last instar, and these larvae 

 were virtually identical to the 441 's, as were the egg masses. In addition, 



