As an annual crop, cotton depends on colonization by predatory and parasitic arthropods for biological pest suppression. These natural enemies help control pests at no cost to cotton producers and should be increasingly effective with the anticipated reduction in overall pesticide loads as the systematic boll weevil eradication programs advance. Knowledge of how predators and parasitoids colonize cotton may allow for habitat manipulations that better use existing populations of beneficial insects. We investigated colonization of cotton fields and subsequent reproduction by Hippodamia convergens (the convergent lady beetle) in an agricultural system where two other crops, corn and grain sorghum, are produced concurrently with cotton. Carbon stable isotopes served as natural marks for predators feeding in these crops and allowed investigation of (1) the time period over which lady beetles colonized cotton from nearby grain sorghum and corn, and (2) if these external crops contributed resources used to produce H. convergens eggs in the cotton crop. Results indicated a four to five week period of concerted movement into cotton by lady beetle adults, with a few individuals continuing to move into cotton late, even as the H. convergens populations in cotton declined. Analysis of egg masses suggested that prey resources in corn and grain sorghum contributed to the production of egg masses in cotton during the six-week period of H. convergens egg production. Further, it was observed that the weeks when strong immigration of adults occurred were coincident with the greatest collections of egg masses produced by adults feeding in corn and grain sorghum. Data from this and other studies emphasize the importance of diverse and continually available resources for predatory insects, and the potential for other crops to contribute to cotton pest control.