1921] Wheeler: Some Social Beetles 85 



on the eggs of a coccid, Saissetia nigra Nietn., on stems of Sea 

 Island cotton. In another paper published during the same year 

 (1911b) he gives a list of 19 species of known zoophagous Amer- 

 ican Itonidids. The list includes species of Endaphis, Arthro- 

 cnodax and Mycodiplosis feeding on mites, an unidentified species 

 of Cecidomyia feeding on the eggs of Cicada septemdecim, sev- 

 eral species of Aphidoletes and Lestodiplosis preying on aphids 

 and of Lestodiplosis, Dentifibula, Diadiplosis, Coccidomyia, Ceci- 

 domyia, Lobodiplosis, Mycodiplosis and Dichrodiplosis preying 

 on various coccids. The Diadiplosis from British Guiana seems 

 to be closely related to the type of its genus. According to KUs- 

 ter (1911), certain European Itonidid larvae have been described 

 by Riibsamen (1899) and Kieffer (1902) as preying on the larvae 

 of gall-makers of the same family. 



Almost as abundant as the Diadiplosis in the beetle colonies 

 is a Hymenopterous parasite of the Pseudococcus, namely Blep- 

 yrus tachigalise Brues (Zoologica III, No. 9), a small Encyrtid of 

 the family Chalcididse. The white larva of this insect lives in the 

 coccid and grows with it, eventually becoming so voluminous that 

 the coccid's body is very convex both dorsally and ventrally. The 

 coccid grows increasingly sluggish and inert and its wax-glands 

 cease to function so that its integument takes on a dull brown- 

 ish color and the wax-pencils disappear from its periphery. The 

 beetles and their larvse are, of course, quite unaware of these pro- 

 found changes in their parasitized cattle and still continue to 

 stroke them, often for long periods, although there is no honey- 

 dew forthcoming as a reward for their efforts. 



When full-grown the larval Blepyrus does not escape from 

 the coccid but remains within it and forms an amber-colored, 

 regularly elliptical cocoon about 2 mm. long and therefore very 

 nearly as large as the coccid, which is now reduced to a mere 

 skin enveloping the huge parasite. The cocoon seems to consist 

 of a hard, glassy substance, possibly a modified silk, and is cov- 

 ered except on its ventral side with small circular spots which 

 represent thinner, depressed areoles in its wall. Where these 

 areoles are lacking on the ventral side the wall is homogeneous 

 and distinctly thinner than elsewhere, but has a number of small 

 pointed projections which seem to pierce the ventral integument 

 of the coccid and to attach the cocoon rather firmly to the wall of 



