BIOLOGY OF SOME COMMON LAMPYRID/E. 73 



pygidium, which it seems may be impalatable to many of their 

 enemies. In the case of luminous larvae there seems to be little 

 possible use for light-organs, unless it is to warn any possible 

 enemies not to eat them. There are many species of insects 

 outside of the family Lampyridae that resemble very closely in 

 appearance certain species of fireflies. If the explanation of 

 this mimicry is that of protection, it would seem that the theory 

 of impalatability must have some basis. The exact purpose 

 for the presence of light-organs in larvae is still indefinitely 

 understood. 



ECONOMIC IMPORTANCE. 



Practically no work has been done on the possible economic 

 value of these insects, and though the data here given are little 

 more than suggestive, every evidence seems to indicate that 

 these insects are of considerable economic importance. The 

 adults are of little value, as most of them probably eat compara- 

 tively little, but the larvae are voracious little creatures which 

 live on and in the ground, and feed on snails, earthworms, 

 cutworm larvae, and, in fact, on larvae of many injurious insects. 

 Most of the soft-bodied animals living on the ground are injurious 

 (unless it is the earthworms), and as the food of firefly larvae is 

 probably limited to these small animals, they necessarily do much 

 economic good in killing them. The slugs and cutworm larvae 

 are among our worst economic pests, and it seems evident that 

 they furnish a large part of the food of these larvae. Since most 

 of the fireflies live two years as larvae, the number of larvae that 

 are feeding on the ground during any season is approximately 

 twice that of the adult fireflies. Anyone who has been out during 

 a June or July evening knows that the fireflies are one of our 

 most abundant insects, which, together with the voracious 

 habits of these larvae leads to the belief that they are of much 

 more economic importance than has been attributed to them 



heretofore. 



SUMMARY. 



1. The fireflies studied are luminous both in the larval and 

 adult states, except Pyropyga fenestralis, which is luminous only 

 during larval life. 



2. In the luminous species the light-organ of the male is 



