LIST OF PRINCIPAL CACTUS INSECTS. 



30 



plied. The very Leathery integument seems to protect the insect 

 againsi desiccation, and in other ways the larva has evidently adapted 

 itself to long periods of wait inn- for favorable food, which, in the arid 

 regions, depends upon the infrequent rains. 



Stictomyia longicornis Bigot. 3 



The Stictomyia longicornis of Bigol is an exceedingly common 

 insect throughout the cactus area. The adults are small (lies with 

 -potted wings. The wings are bent downward at about the middle, 

 so that the name of " droop-winged fly " seems appropriate. (See 

 fig. 8.) The larva* occur along with Copestylum, Volucella, and 

 Hermetia in any part of the cactus plant that may be injured. They 

 also infest wounds made by knives when cuttings are removed for 

 planting. 



The remaining insects 

 listed as scavengers are of 

 less general occurrence than 



the specie- mentioned in / \ . $S*s 



the preceding pages and 

 no special notes have been 

 made upon them. 



LIST OP THE PRINCIPAL 



CACTUS INSECTS OF THE 

 UNITED STATES. 



Fig. 8. — A cactus insect, Bttetomyia longicornis. <i 

 Adult in profile ; o, head ; c, wing. Enlarged. 

 (Original.) 



The following list deals 



primarily with the species 

 attacking or associated 

 with the genus Opuntia and includes all published records of 

 previous investigators. Many forms not restricted to Opuntia are 

 included because, as Mr. Schwarz has pointed out, the insects of that 

 plant are interchangeable with those of other plants of the family 

 Caetacea?. For this reason we have included all of the records of 

 species taken on Cereus giganteus in Arizona by Mr. H. G. Hubbard. 2 

 The names of such species are preceded by an asterisk. We have also 

 included references to some exotic species, principally from Mexico. 

 The published records of cactus insects, including those of Mr. 

 Hubbard, deal with 105 species. The present list includes 324 spe- 

 cies. These are divided, for convenience, into the following groups: 

 Injurious 92. parasitic or predaceous 28, scavengers 73, visitors of 

 flowers 10. incidental 01. 



Order Diptera, Family Ortalids. 



Excepl Platydema inquilinum Linell, which wa 



rat's licst. 



