SPECIES ATTACKING JOINTS INTERNALLY. 27 



some portion infested. The total damage done is consequently con- 

 siderable. 



DIVERSITY OF HABITS. 



All of the Melitaras reared from cactus during the course of this 

 investigation have been identified by Dr. H. G. Dyar as Melitara 

 junctolineella Hulst. However, certain peculiarities in habits have 

 been observed which lead to the suspicion that more than one form 

 may occur. In the region south and east of San Antonio, Tex., the 

 only form occurring makes no opening through the surface of the 

 joint, but packs its excrement in the cavity made in the process of 

 feeding. This form spins a cocoon on the joint or on the ground in 

 case the joint has fallen, but this cocoon is not intermixed with sand 

 or dirt. In the region from Kerrville, Tex., westward, a form occurs 

 which invariably provides an orifice in the joint of the Opuntia 

 through which the excrement is dropped to the ground. This gives a 

 characteristic appearance of the joint which is easily recognized at 

 a considerable distance. This form seems invariably to enter the soil 

 for pupation, and a considerable amount of sand is intermixed with 

 the cocoon spun for the protection of the pupa. 



DESCRIPTION Or IMMATURE STAGES. 



The Larva. 1 



Early stages whitish ; subsequent stages up to the last deep indigo-blue; 

 last stage, 30 to 50 mm. long, conspicuously banded. These bands are dark 

 brown and occupy the posterior quarter of each segment. Head 2.5 mm. 

 wide, dark brown; clypeus rather deeply emargiuate, with light colored band 

 at base. Anal plate almost semicircular in outline, yellow; feet yellow, 

 crochets in ellipses; skin plainly wrinkled on dark annulations, less wrinkled on 

 lighter portions; spiracles elliptical, one and one-half times as long as broad, 

 deep black; thoracic legs light brown; hair very sparse, light yellowish, con- 

 fined to head, sides, and underside. 



The Pupa. 



Incased in loose silken cocoon, sometimes intermixed with sand. 25 mm. long 

 by 9 mm. wide, uniform mahogany blown, spiracles darker; head and thorax 

 transversely rugose; anterior portion of abdominal segments very finely punc- 

 tured; posterior portions more sparsely punctured and slightly wrinkled. 



PARASITE. 



A tachinid parasite of this species, Phorocera comstocli "Williston, 

 is common. It has been reared from material collected throughout 

 the cactus area. 



CONTROL. 



The process of singeing the spines of prickly pear preparatory to 

 feeding undoubtedly destroys many of the eggs of this species. In 



l The larva described by Dr. Dyar as probably that of M. junctolineella (Froc. D. S. 

 Nat. Mus., vol. 25, p. 396) evidently belongs to some other species. 



