231 

 Chondler: Megaloptera 



Family CORYDALIDAE 



Dobsonflies, Fishflies 



This family contains the largest of the Megaloptera; 

 some species have a wing span of more than six 

 inches. However, these large insects are weak flyers. 

 Corydalis is probably the most conspicuous repre- 

 sentative of the family because of the enormously elon- 

 gate mandibles found on the males of some species. 

 Many of the genera have morphological characters that 

 are considered to be quite primitive. 



Relationships. — The genitalia of Dysmicohermes 

 ingens Chandler, with four pairs of paired appendages 

 are undoubtedly very primitive. The wings of Nigronia 

 and Chauliodes with the unbranched forks of the radial 

 sector and the simple anal veins and cells are also 

 primitive. Neohermes and Protochauliode s with R 3 and 

 R 4 fused basally, and A 2 fused with A t , are less 

 primitive in this respect. Corydalis seems more ad- 

 vanced in most characteristics than the other genera. 



The adults are characterized by three ocelli, long 

 antennae which range in shape from filiform to pecti- 

 nate and five-segmented tarsi with the fourth segment 

 cylindrical, not bilobed, and the claws toothed. 



Respiration. — All the larvae have long lateral pro- 

 jections from the sides of abdominal segments one to 

 eight with a small pair on the prolegs. These pro- 

 jections serve as gills in most of the genera. However, 

 in Corydalis they are less modified for this purpose, 

 and there is a tuft of filamentous gills at the base of 

 the lateral projection except in the first instar. 

 Nigronia, which is found in quiet or stagnant water, 

 has the last pair of abdominal spiracles situated at 

 the end of a pair of projections for surface breathing. 



Life history. — The life history of Chauliodes was 

 described by Davis (1903). Eggs are deposited on 

 stones or on branches or under surfaces of bridges 

 that overhang the water. In general, hatching occurs 

 at night five or six days after the eggs were deposited. 

 The larva emerges from the egg near the micropylar 

 projection and drops into the water. The first instar 

 larvae differ from the later instars by having the lat- 

 eral filaments longer and the head large. The fiercely 

 predaceous larvae feed chiefly in the dark and will 

 eat almost anything that they can subdue, including 

 their own kind. Corydalis larvae have been observed 

 to swim either forward or backward with a snakelike 

 motion but are more prone to crawl. The length of the 

 larval period is not known but may be as long as 

 three years. When mature, they seek the bank of the 

 stream above the water level and burrow into the 

 ground or a rotten log and construct a pupal chamber. 

 In this cavity, the pupa forms and the larval skin is 

 shed. The pupal period is about two weeks. D. ingens 

 sheds its pupal skin after emerging from the pupal 

 cell. This cell may be situated twenty to thirty feet 

 from the margin of the stream. 



Maddux (1954) studied the life history of Protochau- 

 liode s aridus in the foothills of the Sierra Nevada 

 and found numerous points of difference from the 

 observations of previous authors. The larvae were 

 found in streams running only during the winter and 



Fig. 8:3. Wings of Neohermes (Chandler, original). 



spring rainy seasons. When the streams dried up in 

 late spring, the mature larvae would burrow beneath 

 large stones in the stream bed and construct pupal 

 chambers. The mandibles, and to a slight extent the 

 legs of the pupae, are functional so that when two 

 pupae are placed together in the same container, 

 usually only one survives. After emergence, the 

 adults deposit their eggs on rocks in the dry stream 

 bed. Upon hatching, the larvae burrow into the loose 

 gravel of the stream bed. This part of the cycle occurs 

 before the onset of summer during which time the 

 ground surface temperatures may exceed 125° F. 

 Specimens kept in dry soil in the laboratory did not 

 become dormant but fed actively on termites and other 

 small insects supplied them. Their abundance and the 

 development of the mouth parts and digestive tract 

 indicate that it is doubtful that adults live more than 

 a few days. Neohermes also pupates in dry stream 

 beds. 



Habitat and distribution. — The larvae prefer coarse 

 or rubble bottoms where they can move about freely 

 below the surface of the stream bed, but occasionally 

 they are found on mud bottoms. Nigronia is found in 

 quiet or stagnant water. They are taken in many 

 habitats such as streams flowing only four months of 

 the year, moderately large rivers, and small streams 

 cascading down the sides of canyons. The frequency 

 of occurrence of the larvae in stream samples would 

 indicate a much larger adult population than is evi- 

 denced by the small amount of material to be found 

 in insect collections. This is no doubt owing to the 

 short life and retiring nature of the adults, whose 

 flying activities are usually restricted to early eve- 

 ning. Some, like P. infuscatus, are active during the 

 middle of the day but fly at large over the countryside 

 so that they are not seen in any numbers along the 

 streams. 



The family is found on all continents in temperate 

 and tropical regions. In North America, members ex- 

 tend into eastern Canada, across the southern United 

 States, and into Canada again along the Pacific Coast. 

 Apparently they are not found in the Rocky Mountains 

 or in most of the Great Basin area. 



Taxonomic characters. — The length and type of 



