3^ J.YT.Y. 



thrans and synu'kcu> and continue witli an account of the symphiles 

 and parasites in the next chapter. 



The Synechthrans. This group, which is not a very large one, 

 comprises a number of agile, carnivorous Staphylinid beetles belonging 

 to the genera Mynncdonia, Myrmcccia, Lamprimis, Qucdins, Xantlw- 

 linns, Mcyastilicns, etc., which lurk in the less frequented galleries of 

 the nests and avoid encounters with the ants. One of the most inter- 

 esting of these genera is Myrmedonia, which is represented by numer- 

 ous species on all the continents and is of generalized and primitive 

 structure, so that it is regarded by Wasmann as related to the ancestral 

 form from which some of the more specialized Staphylinid synoeketes 

 and symphiles have sprung. The European species have been carefully 

 studied by Wasmann (1886). The sooty M. fnncsta (Fig. 224. A') 

 resembles its host, Lasius fuliginosus, in color, and the same is true 

 of the black and red M. humcralis which lives with Formica rufa. 

 The beetles lurk about the burrows and feed on dead or disabled 

 ants, but they also lie in wait near the entrance and destroy solitary 

 ants that are returning to the nest. Wasmann has seen five or six 

 Mynncdonia: fall upon a single ant, tear her limb from limb and 

 then quarrel with one another over the fragments like a pack of 

 hungry hounds. The ants detest these jackals and rush at them 

 with open jaws, but the latter merely turn up their flexible tails and 

 emit a disagreeable secretion. This causes the ants to start back, 

 and the beetles escape. Our American species of Mynncdonia, M. 

 cremastogastris, planifcr and schwarzi, which have been taken in 

 the nests of Cremastog aster lineolata, probably have very similar 

 habits. The South American forms have been found in the nests 

 of Eciton and Pogonomyrmex, the African forms with Dorylns. 

 According to Wasmann (1892) Myrmcecia fnssi, which lives with 

 Tapinoma crraticum, resembles Myrmedonia in its behavior. In this 

 case, too, the synechthran resembles its host, being shining black in 

 color and intermediate in stature between the worker and queen Tapi- 

 noma. It lurks in the unfrequented galleries of the nest and kills the 

 ants at night when they lie huddled together and overcome with the 

 cold. The Tapinoma worker, on meeting the Myrmcecia, turns the tip 

 of her gaster forward and emits her strong-smelling venom. In the 

 United States Mcgastilicus fonnicarins ( Fig. 226), which is not uncom- 

 mon in the large mound nests of Formica cxscctoidcs, is, according 

 to my observations, a typical synechthran. It resembles its host in 

 its black and red coloration and ant-like appearance. When confined 

 with the ants in a small artificial nest, it is invariably killed in the 

 course of a few hours, but in the natural nests it adroitly eludes its host 



