16 ENTOMOLOGICAL SOCIETY 



Apion sordiduin develops in large numbers in the galls of a 

 Cecidomyiid on Bigelovia and causes the death of the gall-maker. 

 Some of our Anthonomus, viz., A. ceneolus (formerly incorrectly 

 referred by me to A. flavicornis) and A. sycophanta furnish other 

 examples of a parasitic mode of life. 



Among the Scolytids no such larval parasitism occurs, but it 

 has long since been observed that in some species the female 

 beetle uses the galleries made by another female, either of the 

 same or another species, to enter the wood for a shorter or longer 

 distance and then to excavate a separate gallery. Eicbhoff men 

 tions several European species in which this habit of taking 

 advantage of the work of other individuals of the same or 

 different species is known to occur, and among our own species 

 I have also observed it. Some years ago I exhibited before our 

 Society (see Proc. i, p. 48) the work of 7"omicus ccelatus, 

 where two females had used the entrance hole previously made 

 by a third female. At another time I cut from the solid wood of 

 a Walnut the network of a gallery in which two different species 

 of Xvleborus (A", fuscatus and pubcscens} had developed so 

 that it was impossible to decide which species was the original 

 author of the burrows and which the intruder. 



In some species of Scolytids this habit is only exceptional, 

 while in others it occurs more frequently, and there is a possibility 

 that in one or the other species it becomes the rule ; in other 

 words, that such species are more or less dependent upon the work 

 done by other species and unable to pierce the bark of a tree by 

 their own effort. 



I do not know whether or not such " parasitic " Scolytids exist, 

 but there is in our fauna a minute species of Crypturgus, the 

 galleries of which, as often as I found them, always started from 

 the main gallery of a Tomicus, usually T. cacograpJnis, More 

 extended observations are, however, necessary to decide whether 

 or not this is the normal habit of this species. I found it first in 

 1876, near Tampa, Fla., under bark of Pinus palustris, and in 

 subsequent years near Washington, D. C., under bark of P. inops. 

 It does not appear to be a very common 'species, but in the fall of 

 1892 quite a number of the galleries were found, though the 

 beetles had in most instances already deserted them. The main 

 gallery starts either rectangularly or obliquely from that of the 

 Tomicus, at such place where no eggs of the host were laid or 

 where the eggs had been destroyed by some predaceous insect. 

 The gallery is either tolerably straight or more or less irregularly 

 curved and of varying length, the longest measuring about 25 

 millimeters. At irregular intervals secondary galleries branch orl 

 which are extremely short, not more than 2 millimeters in length, 

 so that the larvae appear to be more or less stationary. All 

 colonies observed by me were very small, and I never counted 

 more than eight larval galleries in one colony. 



