71 



where it occurs it is by far the most injurious 

 cactus pest, and with the exception of the bugs 

 Chelinidea, spp., is the most destructive enemy 

 of the prickly-pear in the United States. It is 

 found commonly in Southern Texas, being abun- 

 dant from May to September, but is rare in 

 L'jore westerly localities as far as Arizona. 

 Mimorista is parasitised by a hymenopteron, 

 Eiphosoma texana, Cresson (C.I. pp. 20-22, 44). 



The work of this moth was seen commonly 

 on 0. lindheimeri and allied species near San 

 Antonio, Alice, and Brownsville, where there 

 were noticed dead and occasionally deformed 

 joints showing typical injuries on the distal end 

 of one surface (November). Our personal 

 inquiry in the United States did not lead us to 

 regard it as being so important an enemy as 

 Messrs. Hunter and Mitchell did. This may be 

 explained by the fact that our visit was made 

 during late autumn when there was little insect 

 activity. A little later, one member of the Com- 

 mission saw considerable damage caused by an 

 insect, apparently belonging to the same species 

 which was destroying the buds and very young 

 growth of Opuntia dillenii, near Guantanamo, 

 in Cuba. 



As far as known, this insect feeds exclusively 

 on Cactace£e, this opinion being held by Dr. 

 Dyar, of the National Museum, Washington, a 

 leading authority on American Lepidoptera. 



The Cactus Moth Borers, Melitara, spp. 

 (Phycitidffi). 



This genus of Pyralid moths consists of 

 several species, all of which are restricted to the 

 CactaeeEe, the caterpillars feeding on the inter- 

 nal tissues of the joints and stems, and usually 

 bringing about their destruction, being fre- 

 quently assisted in doing so by the larvae of 

 various scavenging diptera, as well as by the 

 invasion of micro-organisms. 



The genus has been described from a syste- 

 matic standpoint by G. D. Hulst (1902, p. 429), 

 in Dr. G. H. Dyar's " List of American Lepi- 

 doptera." The entomologists interviewed were 

 unanimous in their opinion that Melitara, spp., 

 are restricted to the Cactaceaj, especially to 

 Opuntia and Cereus, spp. Plowever, it should 

 be mentioned that Mr. Hulst, in 1890, stated 

 that M. prodenialis is a borer in Yucca and 

 Agave, and that M. dentata lives in Yucca, but, 

 strange to say, he does not include the CactaecEe 

 in their dietary. However, neither the evidence 

 of entomological literature nor that of those 

 investigators competent to express an opinion 

 with regard to this matter, supports him in 

 regard to this matter, nor do our own obser- 

 vations. 



As a rule, each species feeds on more than 

 one kind of cactus, though certain Opuntias 

 seem to be favoured as food-plants, the species 

 or group of species, of course, differing in dif- 

 ferent regions. 



In the Bulletin on Cactus Insects (pp. 25- 

 29), four of these moths are treated of, viz., 

 M. jimctolineella, Hulst, M. dentata, Grote, M. 

 prodenialis, Walker, and M. fernaldialis, 

 Hulst." The observations of the authors, how- 

 ever, refer only to the first named. In addition 

 to these four there is M. parabates, Dyar, from 

 Mexico. The genus extends at least as far south as 

 Guraqao, since Hulst has mentioned that M, 



prodenialis had been received by Dr. Snellen 

 from that island. Moreover, we have observed 

 inland from Barrahona, in South-western San 

 Dommgo, plants of Opuntia dillenii, as well as 

 of another species, which presented the charac- 

 teristic injuries occasioned by Melitara, spp., 

 and from some of these their larvae were taken. 

 Similar injuries were seen also in Barbados, 

 where an Opuntia allied to 0. dillenii was the 

 victim. 



From what has been recorded, and from 

 what we have seen, it would appear that these 

 insects are competent to very seriously injure 

 and even kill priekly-pear plants. Since they 

 are often heavily parasitised, their destructive 

 activity is in such cases not as fully exercised 

 as it would be were parasites absent. In the 

 Bulletin on Cactus Insects (p. 46) there is given 

 a list of those known. Of the three mentioned, 

 one is a beetle, one a hymenopteron, and one a 

 dipteron. Besides these, two hymenoptera are 

 mentioned which are perhaps parasitic. 



The following species may be referred to 

 in more detail. 



Melitara junctolineella, Hulst (1900, p. 

 173). — The adult* is a large greyish moth hav- 

 ing an expanse of about 1% inches, while the 

 larva is at first a whitish but later a deep blue; 

 caterpillar about l^V^ inches long, which becomes 

 marked dorsally with brown bands before pass- 

 ing into the pupa stage. There is said to be 

 only one brood each season. The larvae on 

 hatching from the cylindrical chain of eggs, 

 which are fastened by one end to a spine (C.I., 

 plate 7, fig. 1), penetrate the joint and feed on 

 the internal tissues, forming large excavations 

 which may extend from joint to joint downwards 

 into the stems. As only one or two are found 

 in a joint, it has been suggested that they may 

 be cannibalistic. Sometimes the plant tissues 

 react to the presence of the insect in such a way 

 that proliferation occurs to such an extent that 

 swellings appear on both sides of the segment, 

 the larva at times becoming enclosed. Occasion- 

 ally no larvas are found in such swellings, 

 although evidence of their work is present (C.I., 

 pp. 25-26). Though not abundant in any par- 

 ticular locality, it is widely distributed in Texas. 



It is suggested (C.I., p. 27) that there may 

 be two forms, one from South-eastern Texas and 

 a more westerly variety, since, in addition to 

 certain differences in the structure of the cocoon 

 there are also differences in the method of work- 

 ing. The larva of the former packs the excreta 

 in the cavity formed, and does not make an aper- 

 ture, while that of the latter gets rid of the 

 excreta by means of an opening made through 

 the epidermis of the infected segment. 



A Tachinid fly, PJiorocerca comstocki, Wil- 

 son, is known to parasitise this Melitara (C.I., 

 pp. 25-27). 



Melitara dentata, Grote (1876, p. 158; 1882, 

 p. 29).— Prof. Kellogg (1892, p. 40) has given 

 an account of the various stages of this moth, 

 which he recorded as attacking 0. missouriensis 

 in Eastern Colorado. He stated that the large, 



* Hulst mentions that M. junctolineella is distinguish- 

 able from other species of Melitara by the presence, on the 

 basal line of the front wing, of an outwardly directed 

 dentation, while on the outer line there is a similar one 

 directed inwardly, the two dentations JH*!«ting in ths 

 middle t)ortion of the wing, 



