20 



BULLETIN 124, U. S. DEPARTMENT OF AGRICULTURE. 



of these parasites issued several days later, or 3 per cent. On July 



28 Mr. Newton, encouraged by his first efforts, collected 31 eggs that 

 appeared to be parasitized. Twenty-six of 

 % these produced, in the course of five days, 76 

 parasites, or nearly 3 to each egg. Seventeen 

 freshly laid eggs were exposed to female para- 

 sites by Mr. Newton on August 1, and on 

 August 8 eight of these produced 24 adult 

 parasites, showing the length of the combined 

 egg, larval, and pupal stages to have been seven 

 days. Nine failed to be parasitized, and one 

 produced 5 parasites in six days. On August 

 16 Mr. lYilson collected 19 eggs, 60 per cent 

 of which were parasitized. 



It is thus seen that this tiny parasite is of 

 considerable benefit in reducing the numbers of 

 the alfalfa caterpillar. From the records it 

 seems that the increase of the parasites from 

 July to August was quite rapid. The fact that 

 the life cycle is of so short duration is partially 

 responsible for this, as it doubtless gives a 



chance for two broods of parasites upon the eggs of one generation of 



Eurymus. 



HYMENOPTEROUS PARASITES OF THE CATERPILLARS AND CHRYSALIDS. 



Four species of hymenopterous parasites of the caterpillars 

 and chrysalids were found. Specimens of a Linmerium were reared 



Fig. 7. — Trichogramma 

 miniituni, a parasite of 

 the eggs of the alfalfa 

 butterfly, in act of 

 oviposition in an egg 

 of the hrown-tail moth 

 (Euprootis chrysor- 

 rhcea). Greatly en- 

 larged. (From How- 

 ard and Fiske.) 



Fig. 8. — Limnerium n. sp., an ichneurnonid parasite of the alfalfa caterpillar : Adult. 

 Greatly enlarged. (Original.) 



by the author at El Centro, Cal., in 1910, and what is supposedly 

 the same species was reared in considerable numbers by Mr. L. P. 



