78 



" Signs of /«i«/'y.— Infestation is first indi- 

 cated by an indistinct swelling, usually at the 

 base of a spine, preventing so few characteristics 

 that the party in charge of the plants, and there- 

 fore familiar with the work of the insect, could 

 not be certain of the presence of maggots without 

 cutting into the tissues. This swelling gradu- 

 ally becomes somewhat larger, and eventually an 

 opening appears. The maggots work themselves 

 out and either crawl down the plant or drop to 

 the ground. The desertion of the Cacti is fol- 

 lowed by an infection which results later in a 

 copious exudation of a mucilaginous fluid or sap 

 which hangs in irregular masses an inch or so in 

 length. This infection is followed by the slow 

 death of the affected lobe, and may eventually 

 result in the destruction of portions of the plant 

 or even entire plants. In some instances the work 

 of the maggots is inhabited by a small Ptinid 

 beetle belonging to the genus Gatorama. 



"Early H ist or ij.— This pest was first brought 

 to our notice in 1909 by Mr. George V. Nash, head 

 gardener of the New York Botanical Gardens. 

 The species, according to his statements, occurs 

 in Opuntia hanhuryana from Italy and an Opun- 

 tia from the British "West Indies. Not much fur- 

 ther was heard of this insect until 1913, at which 

 time it was characterised as a very serious pest 

 in a valued collection of Cacti. Earlier it was 

 thought that this midge might be American, since 

 the original distribution of the host-plant is 

 limited to America, though subsequent statements 

 would seem to indicate that this insect may pos- 

 sibly be Italian in origin. Mr. Becker, connected 

 with the New York Botanical Garden, states that 

 some recent cuttings received from Italy and 

 kept in a house well separated from previously 

 infested material were found after a few weeks 

 to be infested by this midge. This is suggestive, 

 though not necessarily conclusive, evidence as to 

 the immediate source, but not to the original 

 home of the insect.* 



"Life History. — Conditions in the Cactus 

 house indicate that this species may breed almost 

 continuously throughout the summer months, and 

 there would seem to be no reason why this pro- 

 cess might not continue during the winter if 

 the plants were not exposed to too low tempera- 

 tures. The midges may be observed in the green- 

 houses, flying around the plants and alighting on 

 the pots or the Cacti. They do not seem to make 

 their way to the windows, and there was no evi- 

 dence of their being captured in spider-webs. A 

 Cactus lobe, apparently in a healthy condition, 

 was cut into, and the interior found to be fairly 

 honeycombed by the maggots. The larvte, on 

 attaining their development, emerge from the 

 plants and may be found lying on the surface 

 of the soil in the pots or in the coal-ashes cover- 

 ing the benches. The transformation to the pupa 

 and emergence of the adults occur in these situa- 

 tions without any difficulty. 



"An effort was made to ascertain the dura- 

 tion of a life cycle but without much success, 

 since the midges do not appear to thrive under 

 ordinary cage conditions, although a small green- 

 house is well adapted to their requirements. 

 Infested Cacti were received and placed in a large 

 breeding-jar, March 10, adults emerging there- 

 from as follows : — April 15th, 1 ; 21st, many ; 

 23rd, 12; May 9th, 8; 10th, 10; 12th, 5; 16th, 

 3 ; 17th, 4 ; 19th, 12 ; 21st, 5 ; 22nd, 3 ; 23rd, 24 ; 



* If Itonida opuntice is restricted to opuntias, then its 

 original home must be in America. — T.H.J. ; H.T. 



27th, 8; 28th, 2; 29th, 4; 31st, 11; June 2nd, 

 4; 4th, 9; 5th, 5; 7th, 4; 9th, 3; nth, 2; 13th, 

 7 ; 25th, 2 ; 26th, 1 ; July 11th, 6 ; 12th, 3 ; 14th, 4. 



"A distinct periodicity will be noted in the 

 appearance of the midges, in that they were 

 much more abundant April 21 and 23, May 19 

 and 23. There was apparently no breeding in 

 this jar, aside from the larva3 already in the soil 

 and the plants attaining maturity. If this be the 

 case it would appear that under certain condi- 

 tions a generation may extend over a period of 

 four months, the flies issuing at irregular inter- 

 vals. This periodicity in the appearance of the 

 midges was also observable in the green-houses, 

 and in at least one case numerous midges 

 appeared in Ijoth at the same date. There may 

 be a period of nearly three weeks between the 

 time the larva leaves the plant and the issuing 

 of the imago, since on March 14 one larva and 

 a pupa were placed in a tumbler with a little 

 sand, and on the 3rd of April a midge issued. 

 It is possible that this period marks the dura- 

 tion of the pupal stage. 



"The larva is about | of an inch or 3 mm. 

 long, rather stout, deep red, and with a well- 

 developed bidentate breastbone. 



"The midges are delicate, dark reddish 

 brown flies, the male having a length of about 

 1 mm., the female 2 mm. Technical descriptions 

 of both sexes have been published* by the 

 author. ' ' 



Asphondylia, spp. 



Aspliondylia opuntice, Felt (1908, p. 376). — 

 This insect attacks both the joint and fruit, more 

 especially the latter, which as a result either are 

 rendered infertile or else shrivel and die. In 

 the former case the seeds are destroyed while 

 the seed receptacle elongates, assumes more or 

 less the character of a small joint, and may give 

 rise to one or more segments which are of some- 

 what smaller size than normal. The insect thus 

 does not seriously injure the attacked plant, but 

 decreases the seed production and thus tends to 

 restrict the spread of Opuntias by seed. _ A 

 figure showing a number of puparia projecting 

 from a shrivelled fruit is given in C.I. (p. 35). 

 The distribution is stated to be from Texas to 

 San Luis Potosi in Mexico, and to Arizona and 

 California, being very common in the last-named 

 State (C.I., p. 34). Records in the Bureau of 

 Entomology, Washington, D.C., show the receipt 

 of the same species from O. o6cidentalis from 

 Southern California, and 0. arhorescens from 

 Arizona. 



A cecidomyiid, presumably this insect, 

 was met with by the Commission, as a tiny 

 orange-coloured larva in "fruits" of 0. fer- 

 ruginispina, 0. convexa, 0. leptocarpa, and 0. 

 lindheimeri at San Antonio, and in the last- 

 named species at Sinton (Texas), as weU as in 

 0. monacantlia at Los Angeles (California). The 

 time of the year in which the inquiry was prose- 

 cuted was unfavourable for the observing of the 

 more pronounced effects of the insect's attack. 



It was in the cactus garden of Mr. B. 

 Mackensen, of San Antonio (Texas), that many 

 species of Opuntia were found to have been 

 attacked, the infested fruit either becoming 

 elongate or else proliferating so that they were 

 not normal. Mr. Mackensen, in his descriptions 

 of certain new species, 0. leptoc arpa (1911, p. 



* Felt, Arm. Rep., New York State Kntomologist. 

 1914. 



