116 ILLINOIS BIOLOGICAL MONOGRAPHS [434 



tergum convex, lateral area of suranal lobe broad, suranal process promi- 

 nent, deep brownish, strongly chitinized, compressed, with two pairs of 

 small but distinct teeth. 



The foregoing definition of the genus is based on one species, Tremex 

 columba. 



Tremex columba Linnaeus. — Length, 40 mm.; width of head, 4 mm.; 

 ultimate segment with setae as follows: tergum near the caudal margin 

 on each side of the median furrow with a small, brown, sharp, hook-like 

 spine, with tiny setae which arise from large calices; ventral side of suranal 

 lobe with such setae; tenth sternum small; small brown spot at the lateral 

 end of anal slit; subanal lobe non-setiferous; subanal appendages wanting; 

 1-8396; G-. 



The eggs of the Pigeon Tremex are oblong-oval, pointed at both ends 

 about 1.2 mm. in length, deposited singly, but in limited area, close to each 

 other; oviposition takes place in early summer, female sometimes fails to 

 withdraw ovipositor and dies in situ; larvae on hatching in the wood make 

 a gallery and feed for probably one season; transformation takes place in 

 the burrow; adults emerge thru circular hole, about 8 mm. in diameter. 

 The larvae are parasitizec by Thalessa lunator and also by Megarhyssa 

 atrata Fabricius, according to Champlain (1921). 



Felt (1906) suggests as remedial measure against this insect, the cutting 

 down and burning of all trees badly infested. Keeping the trees in vigor- 

 ous health is supposed to be sufficient to prevent injury as the larvae work 

 only in weakened or partly decaying wood. 



Family Megalodontidae 



Antennae long, conspicuous, multisegmented, located above or near 

 the ocellarae; larvapods wanting; last abdominal segment rounded, with a 

 pair of bristle-like segmented subanal appendages; larvae feed on herba- 

 ceous plants. 



This family contains four genera, Rhipidioceros, Megalodontes, 

 Melanopus, and Tristactus, and about thirty-five species, which are 

 distributed in Europe,' Asia, and North Africa. Systematists have invari- 

 ably associated this family with the Pamphiliidae, but that this position is 

 unnatural has been conclusively shown by MacGillivray. He has pointed 

 out that it represents a line of specialization very similar to that found 

 in the Siricidae, and that while it is more closely related to this family 

 than to any other, an abundance of characters justify one in considering 

 it as a distinct group. 



Only one species, Megalodontes spissicornis Klug has been recognized 

 in the larval stage. The larvae, according to Hiendlmayr (1878), are found 

 on Lasperfritium latifolium L. in central Europe from the end of July to 



