1908.] NATURAL SCIENCES OF PHILADELPHIA. 601 



speak here of the remarkable illustrations of mimicry and warning 

 colors afforded by the Angolan species, as I have already in preparation 

 a paper on these questions, in collaboration with Prof. E. B. Poulton, 

 F.R.S., of Oxford University, England. I may perhaps with advan- 

 tage, however, refer at this time to the most important food plant of the 

 Angolan Meloidse. This is a small Roseaceous annual which Prof. Engler 

 kindly informed me in Berlin last summer was a species of Tribulus 

 (T. zegheri) which is widely distributed in tropical Africa. Throughout 

 the desert belt of Angola (which extends from the sea to a point 30 

 to 100 miles inland according to the configuration of the country) 

 this plant occurs in enormous masses and is the most important and 

 indeed almost the only food supply of the Meloidse of the region. 

 Most of the genera represented eat it — Mylabris (Ceroctis, Actenodia, 

 Coryna, Decapotoma), Lytta, etc. There are great patches of the 

 yellow blooms and these reveal thousands of beetles; sometimes 

 almost every plant has one or more beetles. Some of the more com- 

 mon species like Mylabris dentata Olivier, Mylabris (Actenodia) chryso- 

 nielina Erichson, Mylabris pluvialis Wellman, Mylabris (Decapotoina) 

 regis Thomas and Mylabris {Coryna) 12-punctata Chevrolat can be 

 obtained in almost endless numbers, and the yellow faeces of the 

 beetles may be seen over the ground like numerous small dots. It is 

 interesting to note that insects like these, which are during their larva? 

 stages all parasitic on other insects, should have such an intimate 

 relation in their imaginal stage to certain plants. Lyttini in their 

 early stages feed on the eggs of Orthoptera and Mylabrini on the young 

 of the same order of insects. In Angola these beetles occur shortly 

 before or about the time when the young Locustidse and Acrididae 

 become numerous, the first rains doubtless having something to do 

 with the hatching of them all. The appearance of the adult Meloidse 

 is almost exactly synchronous with the flowering of the Tribidus, 

 which lasts only a few weeks, and should the beetles be too early or 

 too late in their appearance they (being flower feeders) must inevitably 

 perish from want of food in this desert region where only this one 

 species of Tribulus^ (which is apparently fertilized by the beetles 

 themselves) is abundant enough to support such vast numbers of 

 insects. We see here another illustration of how in the economy of 

 nature the interdependence of several organisms may be very close 



' I have remarked on the relation of this flower to Angolan Meloid^ before 

 the Deutsch. Entomol. Gesellschaft, rid. report in Deiitsch. Ent. Zeitschrift 

 1908 p. 647. 



