﻿36 BULLETIN 1374, U. S. DEPARTMENT OF AGEICULTUEE 



Their life history and habits were studied during the summer by 

 A. C. Johnson and are here given briefly, so far as known. 



Normally the female M. mellitor stings the pink bollworm larva 

 while still in the square, paralyzing it, and deposits an egg on it. In 

 all cases only a single egg was found on one larva. When placed in 

 a cage the adult did not attack loose pink bollworm larvae. The 

 larva of the parasite feeds on the pink bollworm until nothing is 

 left of the latter but a mass of dry skin. 



The larval period of M. mellitor was found in the smnmer to be 

 from 3M to 4 days. The pupal period lasted 4 to 5 days. The 

 adult of this species is apparently a nocturnal worker, as none were 

 ever observed in the field in the daytime. 



Eabrolracon gelecJiiae is more common through the season than 

 M. mellitor. In freshly opened blooms, larvas of the pink bollworm 

 attacked by this parasite were usually found paralyzed and with 

 the eggs of the parasite on them. This indicates that the attack is 

 made after the bloom opens, which appears likely also when we 

 consider the short ovipositor of the adult. It is common to find 4 

 or 5 eggs on 1 larva, and as many as 10 have been observed. In 

 some instances the adult attacked loose pink bollworm larvae in 

 cages. 



The larval and pupal periods of H. gelechiae are about the same as 

 those of M. mellitor. Many adults of the former were observed in 

 the field in the daytime. 



About two-thirds of all paralyzed pink bollworm larvae found in 

 blooms contained neither parasite eggs nor larvae. It is possible 

 that in such cases the eggs or larvae were destroyed by other insects, 

 or the adult of the parasite may often sting the pink bollworm with- 

 out depositing eggs upon it. 



On October 2, some clusters of cocoons and several living pupae of 

 H. gelechiae w^e found in dry blooms collected from the ground. 

 Then 400 closed blooms from 2 to 5 days old were collected from 

 plants. Ninety-seven of these were infested with pink boUworms, 

 of which 10 were parasitized by H. gelechiae. About 2 per cent of 

 the larv£e found in bolls in the fields in December, 1921, were para- 

 sitized by H. gelechiae. These observations show that H. gelechiae 

 seems to prefer attacking larvae in dry blooms and bolls in the fall 

 to attacking them in fresh blooms. During 1921, M. mellitor was 

 more abundant early in the season. 



Several other species of parasites were reared from pink bollworm 

 larvae. These were rare and have not been identified. 



General observations showed that the parasites were not so 

 abundant in 1922 as in 1921. A few parasites apparently identical 

 with M. mellitor were reared from malvaceous plants other than 

 cotton in 1922, but what insects these parasites attacked was not 

 determined. II. gelechiae was not observed emerging from these 

 plants. 



The more or less spasmodic attack of parasites on the pink boll- 

 worm observed in 1921 and 1922 indicates that under conditions 

 existing in the Laguna district no appreciable control of the pest by 

 parasites may be expected, even though a maximum of 33 per cent 

 of the larvae in blooms early in July, 1921, were parasitized. Climatic 

 conditions are evidently much more favorable for the pink bollworm 

 than for the parasites so far observed. 



