134 THE CANADIAN ENTOMOLOGIST. 



in one case 82 seconds, the period always ending with the approach 

 of the ants. 



When I placed a fresh larva, taken from the house, on the stem, as 

 soon as the ants discovered it there was immense excitement among them, 

 and a rush for the last segments. The larva forthwith relieved itself by the 

 excretion of the fluid,and the lubes stood out with domes expanded between 

 the times of sec acting. If I placed a fresh larva on a stem on which were 

 no ants, there ivas no excitement in the larva, no appearance of the tubes 

 and no movement in nth segment. I have watched repeatedly to make 

 sure of this. But if ants were now transferred to the stem, the moment 

 the caressings began the larva changed its behavior. 



From what I have seen, I am led to believe that these tubes are merely 

 signals to the ants, and that when the latter discover them expanded they 

 know that a refection is ready, and rush to the orifice on the nth seg- 

 ment. If the tubes serve any other purpose, I have failed, to discover it. 

 There is no duct visible on the dome of the tube when largely magnified, 

 and the ants seek nothing of the tube or on the 12th segment. It might 

 be supposed that the tubes are used for intimidation, to frighten away 

 enemies, but they certainly are not. They are in some way connected 

 with the organ in n, and in the younger stages, when the larvae suffer 

 most from enemies, neither tube nor this organ is available. The outward 

 openings, and the orifice in 11, are visible in the youngest larval stages, 

 but till near maturity the larva has no use of the tubes and cannot emit 

 the secretion. The ants rarely attempt to caress or solicit young larvae, 

 but pass them by with indifference. When I have occasionally seen an 

 ant run about one of these, the larva manifested great annoyance, throwing 

 up the hinder segments to drive away the intruder. The larva plainly 

 considers the ant as a something to be got rid of— as an enemy. If the 

 tubes could now be thrust out the ant would be attracted, not repelled. 

 But the moment that the tubes are free, and the secretion ready to flow, 

 which I believe to be immediately after 4th and last moult, but may per- 

 haps be just after 3rd moult, and is certainly not earlier than that, the 

 larva submits quietly to the attentions of the ants, and invites and rewards 

 them. Dr. Weismann wrote : " You should try and observe what enemies 

 the larvae have. It is conceivable that there are such enemies as are 

 afraid of ants." 1 find four species of parasites about these larvae. Two 

 are Dipterous. These are of the size of the common house Hy. They 

 deposit eggs on the skin of the larva (in an instance observed, on the 



