PUTNAM ON PULVINARIA INNUMEEABILIS. 318 



of the refracting ends, neither have I been able to detect it in niiujer- 

 ous other specimens of the same date as those figured. Some of these 

 however show irregular refracting spaces along the filament, not con 

 fined to the end, so that I am inclined to regard the arrow-head appear- 

 ance as due to the preparation and not to the structure of the spermato- 

 zoon itself. I have sometimes thought I could detect a slight transverse 

 striation. The filaments represented in Fig. 46 are about 400 1^ long and 

 less than 1 /^ in diameter. It will be noticed that each spermatozoon is 

 considerably longer than tfie entire length of the egg when it is laid. 



Habits.— Hhe male when he first comes out is quite pale colored and 

 soft, but soon becomes darker and stronger. He however at once walks 

 about quite rapidly, and at first pays no attention to the females in his 

 way. On two occasions I have observed the process of copulation. The 

 male mounts the back of the female with his head in the same direction, 

 (fig. 34) and vibrating his antennae rapidly ; he now strokes her actively 

 with his fore feet in the region of her eyes ; then, by means of alternate 

 contractions and expansions of the abdomen, the penis is inserted be- 

 tween the anal valves and into the vulva to the extent of its entire 

 length ; it is then alternately withdrawn and inserted several times ; the 

 vibration of the antennae goes on continually and the stroking with the fore 

 feet takes place at frequent intervals ; several times during the operation 

 the male makes a complete circuit, with the nearly withdrawn penis as a 

 center. The whole process takes about ten minutes. The male then 

 goes off to another female. Whether he ever copulates with more 

 than two females I do not know, but I am inclined to think he does. At 

 any rate his stock of spermatozoa is sufficient for a score or more of fe- 

 males. The proportion existing between the males and females, varies 

 according to circumstances. On healthy trees, and when both males and 

 females are few in number the proportion of males to females is much 

 less than when the trees are unhealthy and the bark lice excessively nu- 

 merous. In the latter case the males often equal or exceed the females 

 in numbers. A suggestion as to the cause of this will be mentioned un- 

 der the head of Diseases. 



I have never seen a male take to wing voluntarily, but they will do so 

 when dropped from an elevation ; those which I observed flew heavily 

 and but a short distance. I do not know whether they are normally di- 

 urnal or nocturnal, but I think niDst likely the latter, as they appear 

 very inactive by daylight.* The life of the male after attaining the use 

 of his wings is very brief, probably never exceeding two or tliree days. 

 The males appear from August 1st to September 15th, but the most of 

 them about August 15th, making the entire life of the male, little if any 

 over eight weeks, while the female lives for thirteen months. 



* Miss Smith who appears to have observed this point more carefully than I have done, 

 Bays however, "They are very active flying about the leaves with great rapidity.'" Prairie 

 Farmer, Jvly 12, 1879. 



