1935] 
Beetles Associated with Ants 
217 
but the majority probably strike at the vitality of the 
society by feeding upon the host brood. The ant brood 
appears to be especially stimulating and may be infre- 
quently raided by species which may or may not live in 
the nest (Park, 1933a), attacked by tolerated nest preda- 
tors (Park, 1932b), or assiduously licked or devoured by 
highly specialized commensals and temporary ectoparasites 
(Park, 1932a, 1933b). 
In the following table the beetles associated with Formica 
ulkei are listed with their seasonal range as far as known 
for the nests, and authority for the data. 
From the above table we find that ten families and fif- 
teen species of beetles have been reported from nests of 
F. ulkei , fourteen of which have been recorded from the 
Illinois mounds. In passing, mention should be made of 
the activity of these beetles during the last three weeks 
of May. Individuals were especially numerous during this 
period ; two species, Atheta polita and Batrisodes globosus 
made repeated short flights of several inches on the eve- 
nings of May 12 and 13, and the syrphid flies of the genus 
Microdon 3 pupated on the mornings of May 17 and 18. 
This seasonal activity is in general agreement with the 
maximum appearance of species and individuals of Cole- 
optera in the Chicago area (Park, 1930), as well as that 
of isolated or specialized communities, e. g. beetle popu- 
lation of fungi (Park, 1931). 
Formica ulkei and F. exsectoides are not only related tax- 
onomically, but ecologically they are very similar and it is 
interesting to observe identity of some, and ecological equiv- 
alence of other, myrmecocoles from the mounds of these 
two species of hosts. The following table (Table II) lists 
those species said to occur in the exsectoides nests as far 
as I have been able to ascertain from the literature. 
So far, no true guest (symphile) has been reported from 
either Formica ulkei or exsectoides nests. A comparison 
of tables I and II shows that three species, Tachywra in- 
curva , Megastilicus formicarius, and Hetserius brunnei- 
pennis, are common to both host ants, and the species of 
3 These flies are at present being determined, and the data concern- 
ing their behavior in the nest, and pupation data are to be given 
later. 
