26 ENTOMOLOGICAL SOCIETY 



talis), and it is not uncommon to find infested trees in which 

 the brood has been almost entirely destroyed by it. No other 

 species exhibits to a more striking extent the predatory habits 

 of the adults, and when they are numerous the fragments of 

 adult Dendroctonus and other barkbeetles destroyed by them 

 will be found in quantities beneath the loose outer bark of trees 

 in the early stages of attack. 



Others, from their clumsy bearing or innocuous appearance 

 as adults, give no hint of their true nature. As a notable 

 example may be mentioned the large-eyed elaters of the genus 

 Alaus, the larvae of which are veritable dragons, and among 

 the most voracious of insects. What their actual food capac- 

 ity may be has never yet been determined, but some idea may 

 be gained by the record of a single larva of Alaus oculatus L., 

 which was collected in April, 1904, when apparently nearly 

 full grown, and during May and June devoured in confine- 

 ment no less than thirteen medium and large-sized cerambycid 

 larvae, pupae, and adults, besides numbers of smaller larvae not 

 counted. No insect appears to be too large and strong to 

 resist them. Alaus myops Fab., which is the principal enemy 

 of Monohammus in pine, will not only prey on the young 

 larvae during its own early stages, but when approaching ma- 

 turity will follow its prey to their pupal cells, deep in the wood, 

 where it will even attack the fully formed and nearly hardened 

 adults. 



The adaptability of many predatory insects to various sur- 

 roundings and their peculiar specialization along certain lines 

 are very remarkable. As in the case of parasites, they are 

 frequently dependent upon more than one species of host. 

 Thanasmms diibius, for example, is unable to arrive at its full 

 development upon the summer broods of Dendroctonus fron- 

 talis, since the barkbeetles will pass through their transforma- 

 tions and emerge before the larvae of the clerid have reached 

 their full growth. In spite of this, the latter rarely find diffi- 

 culty in securing a sufficient food supply in the larvae of the 

 various secondary barkbeetles, as well as of cerambycids, etc. 



Some are very general feeders and others are quite closely 

 confined to certain families, genera, or even species, at least 

 exhibiting marked preferences in this respect. In no instance 

 are they deterred by the location of their prey to anything like 

 the extent that obtains with the hymenopterous parasites. 



Whether or not we may expect to receive practical benefit 

 from a knowledge of the enemies of wood-boring Coleoptera 

 is a question which must be decided by the future. With the 

 exception of a few forms of hymenopterous parasites, which 

 are principally confined to hosts of little economic importance. 



