40 NEW YORK STATE MUSEUM 



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, was found after a few 

 weeks to be infested by this midge. This is suggestive, though 

 not necessarily conclusive, evidence as to the original home of the 

 insect. 



Life history. Conditions in the cactus house indicate that this 

 species may breed almost continuously throughout the winter 

 months, and there would seem to be no reason why this process 

 might not continue during the summer if the plants were not ex- 

 posed to too low temperatures. The midges may be observed in the 

 greenhouses, 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 evidence of their being captured in spider webs. A 

 cactus lobe, apparently in a healthy condition, was cut into and the in- 

 terior found to be fairly honeycombed by the maggots. The larvae, 

 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 covering the benches. The transformation to the pupa and 

 emergence of the adults occur in these situations without any 

 difficulty. 



An effort was made to ascertain the duration of a life cycle but 

 without much success, since the midges do not appear to thrive under 

 ordinary cage conditions, although a small greenhouse is well 

 adapted to their requirements. Infested cacti were received and 

 placed in a large breeding jar March loth, adults emerging there- 

 from as follows: April 15th, i; 21st, many; 23d, 12; May 9th, 

 8; loth, 10; I2th, 5; i6th, 3; 17th, 4; 19th, 12; 21st, 5; 22d, 3; 

 23d, 24; 27th, 8; 28th, 2; 29th, 4; 31st, 11; June 2d, 4; 4th, 9; 

 5th, 5; 7th, 4; 9th, 3; nth, 2; 13th, 7; 25th, 2; 26th, I ; July nth, 

 6; 1 2th, 3 ; 14th, 4. 



A distinct periodicity will be noted in the appearance of the 

 midges, in that they were much more abundant April 21st and 23d, 

 May 19th and 23d. There was apparently no breeding in this jar, 

 aside from the larvae already in the soil and the plants attaining 

 maturity. If this be the case it would appear that under certain 

 conditions a generation may extend over a period of four months, 

 the flies issuing at irregular intervals. This periodicity in the ap- 

 pearance of the midges was also observable in the greenhouse, and 

 in at least one case numerous midges appeared in both at the same 

 date. There may be a period of nearly three weeks between the 

 time the larva leaves the plant and the issuance of the imago, since 



