THE MYRMECOPHILOUS COLEOPTERA 82-7 



the ants. It then seeks its mate and copulation takes place. The beetles 

 are generally to be found on birch shrubs, the young shoots and leaves of 

 which they eat, biting the top shoots right through. The $ then seeks a 

 tree or shrub above or close to a nest of Formica rufa, and drops the eggs 

 on the ground beneath. The eggs are covered by a case, or capsule, which 

 is placed around it by the 5 » ^nd consists of her OAvn excrement. This cover- 

 ing is placed in position with the posterior tarsi, the egg being held in a depres- 

 sion of the abdomen. The covered egg looks exactly like a small bract, 

 and is exceedingly like the end of a birch catkin. The ants pick up the 

 covered egg and carry it into the nest. The young larva, which hatches in 

 about twenty-one days, uses the egg-case as a nucleus on which to build 

 the larval case ; thus very young larval cases have the egg-case still attached 

 to their posterior end. The egg-case has a threefold raison d'etre — to protect 

 the egg and newly-hatched larva, to make the ants believe it is a bit of useful 

 vegetable refuse, and to give the larva a foundation on which to start the 

 larval case. When the larval case grows larger, the egg-case breaks off, 

 and the larva fills up the hole thus formed with the same material as that 

 with which it builds the rest of the case. This material consists of its own 

 excrement mixed with earth, which it prepares with its mandibles. To 

 enlarge the case the larva removes particles from the inside, and plasters 

 them on to the outside. The larva feeds on vegetable refuse in the nest. 

 When changing its skin it fastens the case to some object in the nest. When 

 full groAvn it fastens the case to a piece of wood or twig, and turning com- 

 pletely round, changes to a pupa, facing the broader end of the case. When 

 hatched the beetle gets out of the case at this broader end, by biting a circle 

 round inside it, thus forming a cap, which it forces off. 



Among the species which have been recorded from ants' nests, but are 

 generally found under other circumstances, may be mentioned — Hister 

 marginatus, which has been recorded by Harwood with both Formica rufa 

 and Lasius Juliginosus, but no doubt as chance visitors, as Joy has shown 

 it to be a regular inhabitant of moles' nests. Prionocyphon serricornis has 

 been recorded from nests of F. rufa, but these must have been chance speci- 

 mens, and it has nothing to do with ants. Its larva is semi-aquatic, and 

 lives in holes in trees full of water. I bred a number of specimens from larvae 

 taken in the New Forest in a hole full of water in a felled oak. I reared them 

 for two years in a bowl in my study. Labidostomis tridentata has also been 

 recorded from ants' nests, but again I think it has no connection with ants. 

 I have never found any trace of it, feither larvae or perfect insects, in ants' 

 nests at Pamber Forest, where the beetle is abundant. The eggs which I 

 have observed being laid in nature, are covered with a coating of excremen- 

 tious matter by the female and fastened together, on birch leaves, by long 

 thin threads of excrement. The young larvae feed on algte on bark ; they 

 would never live in, or enter, my observation nests. Figures of these larvae 

 and eggs, and the larva and pupa of the last species, will be found in the 

 Entomologist's Record for May 1908. 



The following is a list of all the known British myrmecophilous species 

 of beetles with their hosts. I would point out that ants' nests beetles in 



