49 



(5) "0. elata, Lk. and Otto— from 

 Dr. Weber, Paris — thorn-bearing 

 variety. ' ' •. 



(6 " 0. elata, L. and 0. — from Vienna 

 Botanical Garden." This and the 

 foregoing recall our spiny pest pear, 

 now naturalised in the Burnett Valley 

 (Gayndah, De^gilbo, etc.). 



(7) "O.stricta, Haw., syn. 0. anacantha, 

 now referred in " Hortus Mortolen- 

 sis" (p. 411) to 0. inermis, DC. 



(8) The commoner Queensland prickly- 

 pear represented by a plant labelled 

 0. inermis, DC— from New South 

 Wales. 



In the Palermo Botanical Gardens, plants 

 evidently identical with our commonest pest 

 species (0. inermis) were labelled as 0. glau- 

 cophylla. 



DESTRUCTION BY INSECT AND OTHER 

 ENEMIES. 



No destructive insect was found, nor did in- 

 quiry reveal the presence of any which produced 

 perceptible injury on the attacked plants. 



Biaspis. — A species of Diaspis was seen moio 

 or less commonly and plentifully on 0. ficus- 

 indica and 0. amyclcea in Spain and Italy, and 

 on the latter in Syria and the three Barba cy 

 States visited, but, even though heavily infested, 

 plants did not show any ill effect. It was also 

 met with on 0. monacantha in some English col- 

 lections. This insect was seen more commonly 

 in Italy in garden collections than on plants 

 growing in the field. It is referred to earlier in 

 this report and has already been recorded as 

 occurring in Queensland (Tryon, 1911 b, p. 18). 

 Pernald (1903) has mentioned the presence of 

 Diaspis echinocacti, Bouche, in Europe and 

 Algeria. 



Coccus spp. — The true cochineal insect 

 Coccus cacti, similar to that raised in the Canary 

 Islands, was seen growing well on cultivated 

 plants of 0. tomentosa in the Jardin d'Essai at 

 Algiers, but not on the smooth Barbary Pig 

 plants (0. ficus-indica) growing in abtindance 

 close by. 0. tomentosa is the species used in the 

 Canary Islands as the "nurse plant" for the 

 young insects, and is identical with the tree-pear 

 occurring at Helidon and elsewhere in Queens- 

 land. No detrimental effect was noticeabje. Tra- 

 but (1910) has referred to the presence of this 

 insect in Algiers. Coccus cacti was formerly 

 cultivated in the warmer parts of Spain, but, as 

 far as known, does not occur there now. In- 

 quiry in the various districts failed to gain any 

 information regarding its existence there at the 

 present time. 



•_ A mealy bug (Rhizococcus, sp.) was occa- 

 sionally seen on Opuntias, especially 0. mona- 

 cantha, in European green-houses, but from 

 information received, it is known to be a general 

 feeder. 



Kuhlgatz (1898) and Hirscht (1899) have 

 given an account of certain Coccids, e.g., RKizo- . 

 coccus multispinosus Kuhlg., and Dactylopiiis±^ 

 longifilis Comstock, which are known to attackij 

 cactus plants in European glass-houses, wherei 

 artificial conditions exist. I 



According to Prof. Stefani Perez, an- 

 other coccid, Icerya purchasi, occasionally attacks 

 0. ficus-indica in Sicily. 



Diptera.—M. J. Goffart informed the Com- 

 mission that a small reddish insect larva at times 

 attacks the ripening fruit of 0. ficus-indica near 

 Tangier, Morocco, but none was found, nor were 

 signs of insect injury to any part of the plant 

 detected at the time of our visit. No observa- 

 tions as to the character and life-history of the 

 larva were made by this botanist. It is probably 

 a Cecidomyiid. 



Prof. Perez, Palermo, referred to the fact that 

 a fruit-fly, Geratitis capitata, attacks the fruit of 

 0. ficus-indica; but it scarcely, if at all, injures 

 the plant, except as a crop-producer. Even if it 

 were injurious to Opuntias, its introduction into 

 Queensland could not, for other reasons, be advo- 

 cated. 



Red Spider.—mvaaht (1899,. p. 797) gives 

 an account of the ravages of the so-called " red 

 spider," Tetranychus telarius, which causes the 

 formation of yellowish, reddish, or rusty spots 

 which soon extend so widely as to cover the sur- 

 face of the infested plant. As a result of the 

 injury, growth ceases and eventually the attacked 

 portions may fall to the ground. This mite is, 

 however, not restricted to the Cactacese, but is 

 a general feeder. 



Snails. — A small species of snail ( ? Helix 

 pisana) known locally as babbaluci, has been 

 referred to by Biuso (1879, p. 104) as feeding 

 on the edges of young tender joints of 0. ficus- 

 inddca in Sicily. It occurs most commonly in 

 districts whose soils are rich in lime, and is 

 especially evident after heavy rain. Biuso states 

 that these molluscs are collected and destroyed 

 before the time of egg deposition. Prof. Perez, 

 of the University of Palermo, mentioned that 

 this snail was at times a serious pest to the cactus 

 in the neighbourhood of that city. As the animal 

 attacks other plants, its introduction into Aus- 

 tralia need not be considered. 



DESTRUCTION BY DISEASE. 



Near Tangier, Morocco, a few clumps of 

 very old prickly -^pear (0. ficus-indica) were 

 found to be suffering from a disease which caused 

 many of the plants to die. An examination of 

 the affected plants, which were all close together, 

 led to the belief that the condition was probably 

 due to deficient root action. Most of the dis- 

 eased pears were, however, producing young 

 joints quite vigorously at the time of the Com- 

 missions 's visit. The malady is probably the 

 same as that referred to later as " cancer," the 

 symptoms being similar. 



Much more attention has been given to 

 prickly-pear diseases in Italy than elsewhere in 

 the Mediterranean area, but an examination has 

 shown that none of these would be of much value 

 in controlling the pest pears of Queensland. 

 They are termed— (1) Male nero; (2) Rot or 

 gangrene (Male di eancro; Marciume, or Krebs) ; 

 (3) Male di verme; (4) Leaf scab. 



' Male Nero. 



* This malady was brought under notice by 

 Sig. A. R. Ragusa, of Palermo, who mentioned 

 that the name was applied to it on account of 



