74 



The Joint Miner, Marmara opuntiella, 



Busck. 

 This small Tineid moth, which was described 

 by Mr. Busck in 1907, is figured in C.I., p. 31. 

 It is referred to as the ' ' leaf miner, ' ' a fine illus- 

 tration of its work being shown in C.I., plate 6. 



The eggs are deposited below the epidermis, 

 where the tiny orange-coloured larvse on hatching 

 begin to make small tunnels or galleries which 

 may cross or coalesce, and which appear through 

 the epidermis as whitish areas. The damage is 

 not serious, as the insects do not penetrate deeply 

 into the segment (C.I., p. 31). 



The work of this insect was seen at San 

 Antonio, Alice, Robbstown, and Brownsville, in 

 Texas, where the common pear (0. lindheimeri 

 and its allies) were found to be attacked. The 

 spiny Mission Pear was seen to harbour this 

 insect at Alice. 



Since Marmara does not do any appreciable 

 injury to Opuntias, its introduction need not be 

 considered. 



An unidentified green lepidopterous larva 

 was found very commonly at Sinton, Texas, 

 within the joints of 0. leptocaulis. All the tissues 

 except the epidermis were eaten out, and a hollow 

 joint or series of joints remained. As a result 

 of its attacks, plants were practically stripped of 

 all their lateral branches. It was quite common 

 to see whole plants killed by it. Since its attacks 

 were confined to 0. leptocaulis, none of the flat 

 Opuntias being attacked, although growing along- 

 side, its introduction into Australia need not 

 be considered. 



Many other Lepidoptera are recorded in the 

 list of Cactus Insects (pp. 44-45), but they are 

 not regarded as important, and some of them 

 moreover, attack other plants. 



The Hemipterous Enemies. 



The most important of these are species of 

 Chelinidea and Narnia, and the Wild Cochineal 

 Insects, all of which are restricted to the 

 Cactaceffi. 



Chelinidea, spp. (Coreidse). 



Chelinidea vittigera, Uhler. — An account 

 of C. vittigera is given in C.I., p. 15. 

 These insects, which are usually nocturnal in 

 their habits, may occur gregariously, feeding on 

 the joints of Opuntia and allied Cactacete. 

 Attacked joints show the presence of lighter- 

 coloured circular spots, a concentric pattern of 

 alternating green and light-coloured areas being 

 sometimes seen. Bach spot marks a point where 

 feeding has taken place. These zones enlarge, 

 and ultimately the joints may assume a sickly 

 appearance. Exceptionally the whole plant is 

 affected, becoming weakened to such an extent 

 that it may fall over, the joints drying up or 

 else becoming the seat of infection by scaven- 

 gers which bring about destruction. The young 

 and adult bugs migrate from these chlorosed 

 plants and resume their activities on a fresh 

 plant. Rooting of fallen segments may take 

 place. 



The breeding habits and life-history are 

 described and a figure of the adult given by 

 MemVH> Hunter, Pratt, and Mitchell (G.I, pp 



17-19). There is continuous breeding through- 

 out the summer and autumn, but during winter 

 the insects hibernate under fallen joints, the 

 roots of grass, &c., in the neighbourhood of an 

 Opuntia. It is stated that they do not seem to 

 travel far from the plant upon which they were 

 produced. This species prefers Opuntias to any 

 other Cactaceous plant. Its range Includes 

 Texas, California, Utah, Colorado; in fact, the 

 Western and Southern States of the United 

 States generally, as it is also known from 

 Louisiana, Alabama, North Carolina, and Vir- 

 gina (C.I., p. 17). Riley and Howard called 

 attention to its presence in Texas (1893, p. 345), 

 and Uhler to its occurrence in Southern Cali- 

 fornia (1894). 



Chelinidea tabulata, Westwood, is said to be 

 found in company with the preceding species in 

 Texas, but this Mexican species is much less 

 common (C.I., p. 19). 



Chelinidea, sp. — An unidentified species of 

 Chelinidea, smaller than C. vittigera, is recorded 

 as attacking 0. ariuscula, 0. versicolor, and 0. 

 fulgida in Arizona. 



In the Bulletin on Cactus Insects (p. 16) 

 it is stated that Chelinidea and its allies are by 

 far the most important iasect pests of Opuntias 

 in the United States, on account of their wide 

 distribution, though the moth Mimorista is prob- 

 ably more destructive in the limited area where 

 it occurs. It is suggested that, in addition to 

 the injury directly traceable to these bi^s, they 

 may act as carriers of the Shot-hole Fungus, 

 Olceosporium lunatum. Dr. Griffiths mentioned 

 during an interview that these bugs caused a 

 more or less marked chlorosis, but that, as a 

 rule, the plants recovered. 



Chelinidea spp. — In spite of the fact that the 

 investigation was made at a time when most of these 

 bugs were hibernating, the Commission saw Cheli- 

 nidea and its work on 0. lindheimeri and allied 

 Opuntias in Texas, at Alice, Laredo, Sinton, 

 and Brownsville, as well as on plants of 0. 

 stricta cultivated at the last-named locality. Its 

 presence was noted at Chico, in Northern Cali- 

 fornia. In Texas, attacked plants were more or 

 less chlorosed, but the extensive injury recorded 

 above was not observed. Hibernating specimens 

 were found near Tucson, Arizona, in tunnels 

 made by Moneilema or Melitara in stems of 0. 

 versicolor and 0. fulgida; and near Wallace, 

 Kansas, in hollowed joints of 0. missouriensis as 

 well as under fallen joints and under debris and 

 grass around the base of this species. 



At Tucson, plants of one of the Cylindro- 

 puntias, 0. spinosior, were found to have dis- 

 eased areas on some of the costse which occur on 

 the stems. These areas were dull black, and 

 from many of them a mucilaginous exudation 

 was evident. No insects were detected in either 

 case inhabiting the parts which had undergone 

 these changes or even on other external parts of 

 the affected plants. However, Chelinidea bugs 

 were discovered in small numbers amongst dead 

 and dry fallen stem-joints on the ground beneath 

 the plants exhibiting these symptoms. 



Though little was seen at the time of the 

 Commission's visit which would lead to the 

 belief that Chelinidea was such an injurious 

 ?5^^^' //* r^ ^*''9^g opinions held by both Mr. 

 W. D. Huntei' and Mr. J. D. Mitchell, entomo- 

 logists whe have had a long experience in Texas, 



