

INSECT ECOLOGY 403 



course, perfectly harmless, but is charged by the natives with causing 

 the death of many a poor horse. 



In the "Valley" insects are abundant in number of species and of 

 individuals; but the term valley does not signify much, ecologically, 

 since it may mean anything from mud flats to desert. On the mesa, 

 dragon flies range five or six miles from any possible breeding place, 

 but the feebler damsel flies never fly far from home. The harlequin 

 cabbage bug is sometimes abundant on Cleome and on cabbage sprouts, 

 but does not seem to be a very serious pest, possibly because it prefers 

 the Cleome. The squash bug, Anasa tristis, is very abundant on culti- 

 vated squashes, and commonly hibernates under yucca stems miles 

 from any cultivated fields. The well-known Carolina locust, Dis- 

 sosteira Carolina, which in the East frequents the driest of situations, 

 in New Mexico clings very closely to the moist valleys, like other eastern 

 forms (as tiger beetles) that occur also in New Mexico. In both east 

 and west, however, the species frequents places of about the same degree 

 of humidity. In the Alkaline Meadow Society, the lesser migratory 

 locust, Melanoplus atlanis, occurs in the more moist situations, and 

 damages alfalfa in the valleys. The red-legged locust is common, 

 inhabiting somewhat drier situations than the last species. Mosquitoes, 

 Culex pipiens, breed in countless millions in the ponds that form in the 

 valley whenever the Rio Grande is high, usually in May and June. All 

 the mosquitoes seen on the mesa come from the valley ; sometimes they 

 are five miles from any possible breeding place. They are carried by a 

 gentle breeze, but a brisk breeze causes them to seek shelter low down 

 among the herbage and not to venture forth. 



The following species, of wide distribution and not characteristic of 

 any particular formation, are of interest as occurring in New Mexico, 

 because they are some of the most familiar insects of more eastern states 

 under quite different climatal conditions. Coleoptera. The metallic 

 leaf-beetle, Chrysochus auratus, occurs on Apocynum as usual, but at an 

 altitude sometimes of ten to eleven thousand feet. Euphoria inda 

 occurs from the valley up to the yellow pine association and doubtless 

 higher. The lady-beetle, Hippodamia convergens, is abundant every- 

 where from the tops of the highest mountains to the lowest parts of 

 New Mexico. Lepidoptera. Colias eury theme, is common in the moun- 

 tains and in the valley wherever there is damp soil, but is absent from 

 the mesa. The checkered white, Pieris protodice, is found from the 

 valley to the spruce association. The painted lady, Pyrameis cardui, is 

 abundant wherever the thistle grows; and more abundant up in the 



