38 



5 c.) There really seems to have been a molt between this pseudi- 

 mago and the perfect male, for in no other way can we account for the 

 difference in form. The antenna) possess the same number of joints (ten) 

 of about the same relative proportion, although joints 3 and 4 are longer, 

 but the incisures are rather better marked. The poisers are lighter in 

 color and less fleshy in appearance, and the curved hook is plainly visi- 

 ble at tip. The abdomen is rather longer, much more slender, and 

 tapers gradually from base to tip. Its segments are well incised, and 

 plainly separable from above. It does not cover the hind coxse and 

 trochanters. The tibiae are longer in proportion to their tarsi. The 

 anal segment gives off two waxy filaments as long as the entire body. 

 These filaments were not noticed in the pseudimago. 



The cocoon itself is rather close though thin, flattened oval, and pure 

 white, about 2 mm long by l mm wide, and is composed of 

 rather coarse wax fibers. (See Fig. 4.) 



According to one season's observations, therefore, 

 this peculiar pseudimaginal form issues under perfect- 

 ly natural conditions several days before the true im- 

 ago; it is active and copulates. We have not observed 

 it develop into a true imago. We have seen the true 

 '■■<{■. imago, however, issue from the cocoon, fully fledged, 



several days later. Why it ever issues as a pseudi- 

 mago we do not know. That this is common is shown 

 by the observations of Signoret, who never saw the 

 fully fledged male. We are not certain whether the 

 copulation of the pseudimago with the female is a per- 

 fect one or is abortive and prompted by premature in- 

 stinct, although the intromittent organ of this form is 

 apparently complete and unsheathed. 



From Mr. Jack's notes and our own observations at 

 Washington we are able to give the round of the in- 

 sect's life in general terms. The young lice are appar- 

 ently born viviparously as with the Mealy Bugs, and 

 issue from their living mothers in late June and early 

 July and scatter actively over the tree, the majority of 

 them with TJlmus fulva in which the twigs are pube- 

 scent or bristly, settling temporarily upon the leaves, 

 mainly upon the upper surface in the angles of the midrib and princi- 

 pal veins, but also upon the under surface. With Ulmus racemosa, how- 

 ever, the twigs being smooth, large numbers settle about the buds and 

 on the surface of the twig, many others also occurring on the leaves. 

 With Ulmus montana, which is the species upon which we have princi- 

 pally studied them, they settle very abundantly upon the under sides 

 of the leaves along the midrib and preferably just at the forkings of the 

 veins. We have never found them settled upon the upper surface of the 

 leaves, nor, in this stage, upon the twigs. 



Fig. 4. — GossYi'A- 



"B1A DLMI : CoCOOIl of 

 male, showing aual 

 filaments and edges 

 of wings extruding — 

 greatly enlarged 

 (original). 



