62 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



/ 



SOME NOTES ON INSECT ABUNDANCE IN TEXAS IN 1911. 



BY W. D. HUNTER, 

 Bureau of Entomology, U.S. Dept. of Agriculture. 



These notes are not presented with the idea that the}" are 

 of any special importance, hut it is believed that when similar 

 notes are placed on record from different seasons that some 

 light may possibly be thrown upon the laws which govern 

 the sudden increase of species. In the case of injurious forms 

 this may be of economic importance. 



Fluctuations in numbers of insects from season to season 

 are apparently brought about primarily by enemies and by 

 climatic conditions. The conditions in Texas in 1911 were 

 very peculiar. The most striking feature was a marked de- 

 ficiency in precipitation. Early in the spring the departure 

 from the normal began and continued until about the first 

 of August. So great was the effect of the drought that all 

 vegetation in the State was affected. The corn crop was 

 practically ruined and a similar disaster would have overtaken 

 the cotton crop if it had not been for rains which came just 

 before they would have been too late. Drought prevailed 

 also during the season of 1910 and again in 1909. In fact, 

 1911 was the culmination of three years which were marked 

 by extreme conditions of dryness. At the same time tempera- 

 tures had occurred which theoretically would seem to be de- 

 cidedly adverse to insects. One of the most remarkable occur- 

 rences of this kind was the killing frost of October 29, 1910, 

 which took place considerably in advance of the normal date. 

 All these circumstances combined to cause a set of conditions 

 which would have been supposed to have contributed to the 

 scarcity of insects rather than to their abundance. On this 

 account the notes to be presented may be of some special 

 interest. It may be stated parenthetically that the cotton 

 boll weevil was the onl} r important species which seems to 

 have behaved as would have been expected. It was properly 

 subjugated by the drought. 



The most conspicuous example of insect abundance in 

 1911 in Texas was that of Alabama argillacea^llon. This 

 matter has been discussed elsewhere recently and will be passed 

 over in this connection, more especially since it concerns a 

 species which became abundant by an invasion of the country 

 and not by sudden increase from a local source. 



Two enemies of the cotton worm assumed very large num- 

 bers. One of these was Calosoma lugubre Say. This is not 

 an uncommon insect in Texas and is found at the electric 

 lights in some abundance during practically every season. 



