81 



■with, certain exceptions, should be introduced 

 and that Dr. Howard's generously proffered 

 assistance should be availed* of ; but that the 

 work could not be immediately entered upon 

 without its approval and authority. Besides, it 

 would be necessary for the Queensland Govern- 

 ment to provide the necessary insectary and ento- 

 mological staff for handling in our State what- 

 ever insects should be received. 



The ' ' Eed Spider, ' ' Tbtranychus opuntm;. 

 Banks. 



Besides the numerous insect enemies enume- 

 rated above, there is an arachnid, Tetranychus 

 opuntim, Banks (1908, p. 36), which Dr. D. 

 Griffiths regards as a serious pest of both wild 

 and cultivated Opuntias, but particularly of the 

 latter. He has given an account of the work 

 attributed to it (1908, pp. 29, 30). The parts 

 around the areoles are first attacked, a yellowish, 

 corky tissue being formed on the surface by the 

 plant as a result of the injury. This discoloured 

 area may extend over the greater part of the 

 joint. Owing to the cracking of this callus, a 

 mucilage may escape from the joint. Dr. 

 Griffiths states that no plants were observed to 

 have been killed by this "red spider," which is 

 said to be most abundant in the winter, about 

 March. The ! injury is more commonly seen 

 where the Opuntias are crowded together. 



The condition referred to by Dr. Griffiths 

 was seen on 0. lindheimeri under cultivation at 

 San Antonio, as well as at Brownsville. The 

 Curator of the Plant Introduction Gardens at 

 Chico, California, stated that Tetranychus was 

 very common in the greenhouses during March 

 and April, and, on account of the injury caused 

 by it, fumigation had to be resorted to in order 

 to control the pest. 



According to Hirscht (1899, p. 797), T. tela- 

 rius is a formidable enemy of the Caetacease in 

 European collections. It causes the formation of 

 yellow, reddish, or red-brown spots which soon 

 extend over the surface of the whole plant, 

 followed by a cessation of growth, and even a 

 dropping to the ground of the upper parts of 

 the plant. 



As "red spiders" are not restricted in their 

 dietary to the Cactaceae, their introduction need 

 not be considered. 



UTILISATION AS FOOD FOR MAN. 



Comparatively little use is made of the 

 prickly-pear or its fruit as food for man in the 

 United States, while in the neighbouring Repub- 

 lic of Mexico the fruit especially forms a very 

 important article of diet (Griffiths and Hare, 

 1907 b) . This is due to the fact that the species 

 found indigenous to the former country do not 

 produce fruit comparable as a food with those 

 derived from the various Opuntias occurring 

 wild in the Mexican highlands. Certain species 

 grouped under the term " Mission Pear " have 

 been long introduced from Mexico into the 

 warmer parts of the United States,- and these are 

 partly cultivated by the Mexican population there 

 for the sake of the fruit, for which there is a local 

 demand. Among the indigenous species whose 

 fruits are oceasionally utilised in this way are 



Carnegiea gigantea, Opuntia dulcis* and the 

 group of cacti (Echinocereus, spp.) known col- 

 lectively as pitalla or Mexican strawberries. A 

 detailed analysis of the rind, pulp, and of the 

 fruit (minus the peel and seeds) of some prickly- 

 pears native to the United States has been pub- 

 lished by Drs. Griffiths and Hare (1907 b, pp. 15, 

 16, 32-42). t 



In order to meet the demand for edible 

 prickly-pear fruit made by Southern European 

 immigrants (chiefly Italians) in the United 

 States, a steady importation of the fruit of 0. 

 ficus-indica into New York goes on from Italy 

 and Sicily (Griffiths, 1905, p. 41). 



The fruits of some of the indigenous species, 

 e.g., 0. dulcis, are occasionally made into pre- 

 serves. The pulpy central mass of the "nigger- 

 head" or barrel cactus, Echinocactus wisUzeni, 

 Engelm., and its allies is commonly used in Ari- 

 zona and Southern California in the manufac- 

 ture of a product termed "cactus candy, "this 

 portion being cut into pieces which become infil- 

 trated with sugar by being boiled in syrup. The 

 candy may be variously coloured. 



Mr. Luther Burbank, of Santa Rosa, Cali- 

 fornia, has given careful attention to the improve- 

 ment of the fruit-bearing and stock-feeding capa- 

 bilities of certain varieties belonging to the 0. 

 decumana group of species. 



UTILISATION AS POOD FOR CATTLE. 

 A great deal has been written in the United 

 States on this subject, particularly by Dr. Grif- 

 fiths and Dr. Hare. Amongst others who have 

 devoted much attention to this economic aspect 

 are Dr. Wooten (1911) in New Mexico, and Prof. 

 Thornber (1911) in Arizona. One of the earliest 

 to publish the results of his analyses of prickly- 

 pear was Harrington (1888, 1895). Goss (1896, 

 1903), Forbes (1904), and Vinson (1911) have 

 added further information, but the greatest 

 amount of work along the lines of chemical 

 analyses, followed up by feeding tests, has been 

 carried out by the two first-named authors, 

 Griffiths and Hare. 



As the conditions of growth of prickly-pear 

 in the United States of America are so different 

 to those in Australia, a summary of the work 

 done will suffice. 



Prickly-pear as a Farm Crop.— The Federal 

 Agricultural Department at Washington, D.C., 

 as w£ll as those of New Mexico and Arizona, are 

 endeavouring to induce people to plant out cactus 

 as an emergency fodder against times of drought. 

 In fact, Dr Griffiths advocates the growth of 

 many species of prickly-pear as farm crops 

 (1908 a, 1908 c, 1909 a, 1912 a), and states what 

 conditions of climate are necessary for their 

 proper development. 



In his paper on "The Prickly Pear and 

 other Cacti as Food for Stock" (1905), Dr. Grif- 

 fiths referred to various methods of singeing and 

 chopping the pear. He pointed out its value dur- 

 ing drought, especially if some more concentrated 

 food be added. Its succulence was found to be 



* Keferred to by Griffiths and Hare (1907 b, p. 62) as 

 O. Icevis ?, Coulter 



+ Mrs B L. de Grafie (1896, p. 169) has referred to 

 the chemical properties of prickly-pear as weU as to some 

 methods of utilisation of the fruit. 



