You can find a description of this species in page 38 of the book “The Coccinellidae of Louisiana (Insecta: Coleoptera)” – By J.B. Chapin (1974). This book can be found through this link:
http://www.texasento.net/Coccinellidae_LA.pdf
Additionally, the following link can also be useful:
Booth and Pope had revised this genus in 1986. Attachment is the full text of this paper. You can find the detailed descriptions and illustrations of Cryptolaemus montrouzieri and the resembling species.
if you just want to confirm the identity of samples, you can extract the DNA of them individually, do DNA barcoding with exited mtCOI primers and identify the taxamony of them by using the BOLD system (http://www.boldsystems.org/index.php/IDS_OpenIdEngine). it will save you a lot of time especially when this species, with already sequenced mt COI sequence, was confirmed previously based on phenotype by experts (http://www.boldsystems.org/index.php/Taxbrowser_Taxonpage?taxon=Cryptolaemus+montrouzieri&searchTax=).
Based on DNA Barcoding, you can used different life stageas well as incomplete samples and easily identify the species.
You can also check the Coccinellidae from South America which has good illustrations for identification of all the species in the following link http://www.coccinellidae.cl/